s390/net: fix format string mismatches

cppcheck blamed some issues in drivers/s390/net/...
They are fixed here.

Signed-off-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: Frank Blaschka <blaschka@linux.vnet.ibm.com>
Reported-by: Toralf Foerster <toralf.foerster@gmx.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/s390/net/qeth_l3_main.c b/drivers/s390/net/qeth_l3_main.c
index c58f82a..14e0b58 100644
--- a/drivers/s390/net/qeth_l3_main.c
+++ b/drivers/s390/net/qeth_l3_main.c
@@ -63,7 +63,7 @@
 int qeth_l3_string_to_ipaddr4(const char *buf, __u8 *addr)
 {
 	int count = 0, rc = 0;
-	int in[4];
+	unsigned int in[4];
 	char c;
 
 	rc = sscanf(buf, "%u.%u.%u.%u%c",