rtc: m41t80: include <linux/kernel.h> for printk()

The driver uses printk(), but does not include <linux/kernel.h> -- add it.
Signed-off-by: NMaciej W. Rozycki <macro@linux-mips.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Alexander Bigga <ab@mycable.de>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/rtc/rtc-m41t80.c

@@ -15,6 +15,7 @@
 
 #include <linux/module.h>
 #include <linux/init.h>
+#include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/string.h>
 #include <linux/i2c.h>