arm: fix implicit memset/string.h usage in various arch/arm files

To fix things like this:

arch/arm/mach-omap2/usb-tusb6010.c:58: error: implicit declaration of function 'memset'
arch/arm/kernel/leds.c:40: error: implicit declaration of function 'strcspn'
arch/arm/kernel/leds.c:40: warning: incompatible implicit declaration of built-in function 'strcspn'
arch/arm/kernel/leds.c:45: error: implicit declaration of function 'strncmp'
arch/arm/kernel/leds.c:55: error: implicit declaration of function 'strlen'
arch/arm/kernel/leds.c:55: warning: incompatible implicit declaration of built-in function 'strlen'
arch/arm/mach-omap2/clockdomain.c:52: error: implicit declaration of function 'strcmp'

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
index 62510ec..9e2179f 100644
--- a/arch/arm/mach-omap2/display.c
+++ b/arch/arm/mach-omap2/display.c
@@ -15,6 +15,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>