[S390] tape: remove unused/not handled return codes

Return codes are on purpose not handled or used. So remove them.

Acked-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/drivers/s390/char/tape_std.c b/drivers/s390/char/tape_std.c
index 3c3f342..e765017 100644
--- a/drivers/s390/char/tape_std.c
+++ b/drivers/s390/char/tape_std.c
@@ -564,7 +564,6 @@
 tape_std_mtreten(struct tape_device *device, int mt_count)
 {
 	struct tape_request *request;
-	int rc;
 
 	request = tape_alloc_request(4, 0);
 	if (IS_ERR(request))
@@ -576,7 +575,7 @@
 	tape_ccw_cc(request->cpaddr + 2, NOP, 0, NULL);
 	tape_ccw_end(request->cpaddr + 3, CCW_CMD_TIC, 0, request->cpaddr);
 	/* execute it, MTRETEN rc gets ignored */
-	rc = tape_do_io_interruptible(device, request);
+	tape_do_io_interruptible(device, request);
 	tape_free_request(request);
 	return tape_mtop(device, MTREW, 1);
 }