android-common: include linux/slab.h

Change-Id: Ib9655177bfaf00bd5682e1ac0d7e813e16a47eea
diff --git a/drivers/staging/android/timed_gpio.c b/drivers/staging/android/timed_gpio.c
index a646107..a64481c 100644
--- a/drivers/staging/android/timed_gpio.c
+++ b/drivers/staging/android/timed_gpio.c
@@ -16,6 +16,7 @@
 
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/slab.h>
 #include <linux/hrtimer.h>
 #include <linux/err.h>
 #include <linux/gpio.h>