bnxt_en: Separate RDMA MR/AH context allocation.

In newer firmware, the context memory for MR (Memory Region)
and AH (Address Handle) to support RDMA are specified separately.
Modify driver to specify and allocate the 2 context memory types
separately when supported by the firmware.

Signed-off-by: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>