[WATCHDOG] SAM9 watchdog - update for moved headers

The architecture header files were recently moved from
include/asm-arm/mach-at91/ to arch/arm/mach-at91/include/mach/.
The SAM9 watchdog driver still includes a header from the old location.
Signed-off-by: NAndrew Victor <linux@maxim.org.za>
Signed-off-by: NWim Van Sebroeck <wim@iguana.be>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>

drivers/watchdog/at91sam9_wdt.c

@@ -30,7 +30,7 @@
 #include <linux/bitops.h>
 #include <linux/uaccess.h>
 
-#include <asm/arch/at91_wdt.h>
+#include <mach/at91_wdt.h>
 
 #define DRV_NAME "AT91SAM9 Watchdog"