RDMA/bnxt_re: remove redundant initialization of rc to zero

rc is initialized to zero but is then updated by calls to
bnxt_qplib_free_fast_reg_page_list and/or bnxt_qpliob_free_mrw
so the initialization is redundant and can be removed.

Detected with CoverityScan, CID#1408448 ("Unused Value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -2818,7 +2818,7 @@ int bnxt_re_dereg_mr(struct ib_mr *ib_mr)
 {
 	struct bnxt_re_mr *mr = container_of(ib_mr, struct bnxt_re_mr, ib_mr);
 	struct bnxt_re_dev *rdev = mr->rdev;
-	int rc = 0;
+	int rc;
 
 	if (mr->npages && mr->pages) {
 		rc = bnxt_qplib_free_fast_reg_page_list(&rdev->qplib_res,