Add helper functions to access the IDRs by port-space and port number.

Pass around the port-space enum in cma.c instead of using pointers to
port-space IDRs.
Signed-off-by: NHaggai Eran <haggaie@mellanox.com>
Signed-off-by: NYotam Kenneth <yotamke@mellanox.com>
Signed-off-by: NShachar Raindel <raindel@mellanox.com>
Signed-off-by: NGuy Shapiro <guysh@mellanox.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>