MFC r347272:
Query and cache PCAM, MCAM registers on initialization in mlx5core.

On load_one, we now cache our capabilities registers internally, similar
to QUERY_HCA_CAP. Capabilities can later be queried using macros
introduced in this patch.

Linux commit:
71862561f3a62015a11de16d1c306481e8415c08

Submitted by: slavash@
Sponsored by: Mellanox Technologies