net/rds: Set fr_state only to FRMR_IS_FREE if IB_WR_LOCAL_INV had been successful

Fix a bug where fr_state first goes to FRMR_IS_STALE, because of a failure
of operation IB_WR_LOCAL_INV, but then gets set back to "FRMR_IS_FREE"
uncoditionally, even though the operation failed.

Signed-off-by: Gerd Rausch <gerd.rausch@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>