MFC r283612, r290710, r291694, r291699 and r291793:

MFC r283612, r290710, r291694, r291699 and r291793:
- Add SIOCGI2C ioctl support to the driver. Would work only on ConnectX-3
  with fresh firmware. The low level code is based on code provided by
  Mellanox.
- Fix print formatting compile warnings for Sparc64 and PowerPC platforms.
- Updated the mlx4 and mlxen drivers to the latest version, v2.1.6:
  - Added support for dumping the SFP EEPROM content to dmesg.
  - Fixed handling of network interface capability IOCTLs.
  - Fixed race when loading and unloading the mlxen driver by applying
    appropriate locking.
  - Removed two unused C-files.
- Convert the mlxen driver to use the BUSDMA(9) APIs instead of
  vtophys() when loading mbufs for transmission and reception. While at
  it all pointer arithmetic and cast qualifier issues were fixed, mostly
  related to transmission and reception.
- Fix i386 build WITH_OFED=YES. Remove some redundant KASSERTs.

Sponsored by:	Mellanox Technologies
Differential Revision:	https://reviews.freebsd.org/D4283
Differential Revision:	https://reviews.freebsd.org/D4284

git-svn-id: svn://svn.freebsd.org/base/stable/9@292115 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f