IB/srp: Move code out of a loop

Since all srp_map_finish_fr() callers pass a non-zero value as
the fourth argument (sg_nents), the sg_nents == 0 check in that
function can be removed. Add a count == 0 check in the caller
of that function.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Laurence Oberman <loberman@redhat.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/ulp/srp/ib_srp.c

@@ -1315,9 +1315,6 @@ static int srp_map_finish_fr(struct srp_map_state *state,
 
 	WARN_ON_ONCE(!dev->use_fast_reg);
 
-	if (sg_nents == 0)
-		return 0;
-
 	if (sg_nents == 1 && target->global_mr) {
 		srp_map_desc(state, sg_dma_address(state->sg),
 			     sg_dma_len(state->sg),
@@ -1439,6 +1436,9 @@ static int srp_map_sg_fr(struct srp_map_state *state, struct srp_rdma_ch *ch,
 	state->fr.end = req->fr_list + ch->target->cmd_sg_cnt;
 	state->sg = scat;
 
+	if (count == 0)
+		return 0;
+
 	while (count) {
 		int i, n;