This patch adds following changes to support RoCE-v2
in the UD path.

 * During AH creation GID-type is resolved for a given gid-index.
 * Based on GID-type protocol header is built.
 * Work completion reports network header type and set
   IB_WC_WITH_NETWORK_HDR_TYPE flag in wc->wc_flags to indicate
   that the network header type is valid.
Signed-off-by: Somnath Kotur <somnath.kotur@avagotech.com>
Signed-off-by: Devesh Sharma <devesh.sharma@avagotech.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>