cxgbe(4): Very basic T6 awareness. This is part of ongoing work to

cxgbe(4): Very basic T6 awareness.  This is part of ongoing work to
update to the latest internal shared code.

- Add a chip_params structure to keep track of hardware constants for
  all generations of Terminators handled by cxgbe.
- Update t4_hw_pci_read_cfg4 to work with T6.
- Update the hardware debug sysctls (hidden within dev.<tNnex>.<n>.misc.*) to
  work with T6.  Most of the changes are in the decoders for the CIM
  logic analyzer and the MPS TCAM.
- Acquire the regwin lock around indirect register accesses.

Obtained from:	Chelsio Communications
Sponsored by:	Chelsio Communications