cxgb4: Add HMA support

HMA(Host Memory Access) maps a part of host memory for T6-SO memfree cards.

This commit does the following:
- Query FW to check if we have HMA support. If yes, the params will
  return HMA size configured in FW. We will dma map memory based
  on this size.
- Also contains changes to get HMA memory information via debugfs.

Signed-off-by: Arjun Vynipadath <arjun@chelsio.com>
Signed-off-by: Santosh Rastapur <santosh@chelsio.com>
Signed-off-by: Michael Werner <werner@chelsio.com>
Signed-off-by: Ganesh GR <ganeshgr@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>