s5pc1xx: SMDKC100: fix compile warnings

fix the following compile warnings
warning: dereferencing type-punned pointer will break strict-aliasing rules

Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>
diff --git a/drivers/serial/serial_s5pc1xx.c b/drivers/serial/serial_s5pc1xx.c
index 64c1dcc..68c06a9 100644
--- a/drivers/serial/serial_s5pc1xx.c
+++ b/drivers/serial/serial_s5pc1xx.c
@@ -74,7 +74,7 @@
 	val = pclk / baudrate;
 
 	writel(val / 16 - 1, &uart->ubrdiv);
-	writel(udivslot[val % 16], &uart->udivslot);
+	writew(udivslot[val % 16], &uart->udivslot);
 }
 
 /*