RDMA/cma: Do not query GID during QP state transition to RTR

When commit [1] was added, SGID was queried to derive the SMAC address.
Then, later on during a refactor [2], SMAC was no longer needed. However,
the now useless GID query remained.  Then during additional code changes
later on, the GID query was being done in such a way that it caused iWARP
queries to start breaking.  Remove the useless GID query and resolve the
iWARP breakage at the same time.

This is discussed in [3].

[1] commit dd5f03be ("IB/core: Ethernet L2 attributes in verbs/cm structures")
[2] commit 5c266b23

 ("IB/cm: Remove the usage of smac and vid of qp_attr and cm_av")
[3] https://www.spinics.net/lists/linux-rdma/msg63951.html

Suggested-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>