cxgbe(4): Update T5 and T4 firmwares to 1.15.28.0.

cxgbe(4): Update T5 and T4 firmwares to 1.15.28.0.

These firmwares were obtained from the beta "Chelsio T5/T4 Unified Wire
v2.12.0.2 for Linux" release.  Changes since last release are listed in the
"Release Notes" accompanying the beta release and are copy-pasted here as well.

The plan is to have only GA'd firmwares in any -STABLE FreeBSD branch so I'll
MFC this (after 2 months) only if it ends up in a GA release.

================================================================================
================================================================================

22.1. T5 Firmware
+++++++++++++++++++++++++++++++++

Version : 1.15.28.0
Date    : 02/29/2016
================================================================================

FIXES
-----

BASE:
 - Fixed an issue in FW_RSS_VI_CONFIG_CMD handling where the default ingress
   queue was ignored.
 - Fixed an issue where adapter failed to load fw by adjusting DRAM frequency.
 - Fixed an issue in watchdog which was causing VM bring-up failure after
   reboot.
 - Fixed 40G link failures with some switches when auto-negotiation enabled.
 - Fixed to improve on link bring-up time.
 - Per port buffer groups size doubled to improve performance.
 - Fixed an issue where bogus d3hot bits were set causing traffic stall.
 - Fixed an issue where sometimes adapter was not seen after reboot.
 - Fixed an issue where iWARP was crashing in conjunction with traffic
   management.
 - Fixed an issue where link failed to come up after removing twinax cable and
   inserting optical module.

OFLD
 - Fixed a potential iSCSI data corruption issue by disabling RxFragEn flag.

FOiSCSI
 - Fixed an issue in recovery path where connection was getting closed before
   recovery processing was done.
 - Fixed an issue in TCP port reuse.
 - Fixed an issue in recovery path when large number (>64) of iSCSI connections
   were in use.
 - Returned ENETUNREACH if IP was not been provisioned yet and driver tried to
   use given inerface.

ENHANCEMENTS
------------

BASE:
 - Added new interface to program DCA settings in SGE contexts; allow 32-byte
   IQE size
 - Added PTP interface fw_ptp_ts to support PTP Frequeny and Offset adjustment.
 - Added MPS raw interface.

ETH:
 - New mailbox command FW_DCB_IEEE_CMD api added for IEEE dcbx.

OFLD:
 - WR opcode is returned to host in cqe error response.

================================================================================
================================================================================

22.2. T4 Firmware
+++++++++++++++++

Version : 1.15.28.0
Date    : 02/29/2016
================================================================================

FIXES
-----

BASE:
 - Fixed an issue in FW_RSS_VI_CONFIG_CMD handling where default ingress queue
   was ignored.
 - Fixed an issue in watchdog which was causing VM bring-up failure after
   reboot.
 - Per port buffer groups size doubled to improve performance.
 - Fixed an issue where iWARP was crashing in conjunction with traffic
   management.

FOiSCSI:
 - Fixed an issue in recovery path where connection was getting closed before
   recovery processing was done.
 - Fixed an issue in TCP port reuse.
 - Fixed an issue in recovery path when large number (>64) of iSCSI connections
   were in use.
 - Returned ENETUNREACH if IP had not been provisioned yet and driver tried to
   use given inerface.

ENHANCEMENTS
------------

BASE:
 - Added MPS raw interface.

ETH:
 - New mailbox command FW_DCB_IEEE_CMD api added for IEEE dcbx.

================================================================================

Obtained from:	Chelsio Communications
MFC after:	2 months
Sponsored by:	Chelsio Communications