RDMA/core: Cosmetic change - move member initialization to correct block

old_pd is used only if IB_MR_REREG_PD flags is set.
For readability move it's initialization to where it is used.

While there rewrite the whole 'if-else' block so on error jump directly
to label and no need for 'else'
Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -819,20 +819,19 @@ static int ib_uverbs_rereg_mr(struct uverbs_attr_bundle *attrs)
 		}
 	}
 
-	old_pd = mr->pd;
 	ret = mr->device->ops.rereg_user_mr(mr, cmd.flags, cmd.start,
 					    cmd.length, cmd.hca_va,
 					    cmd.access_flags, pd,
 					    &attrs->driver_udata);
-	if (!ret) {
+	if (ret)
+		goto put_uobj_pd;
+
 	if (cmd.flags & IB_MR_REREG_PD) {
+		old_pd = mr->pd;
 		atomic_inc(&pd->usecnt);
 		mr->pd = pd;
 		atomic_dec(&old_pd->usecnt);
 	}
-	} else {
-		goto put_uobj_pd;
-	}
 
 	memset(&resp, 0, sizeof(resp));
 	resp.lkey      = mr->lkey;