drivers/rtc/rtc-at91rm9200.c: include <linux/uaccess.h>

Silences the following checkpatch warning:
  WARNING: Use #include <linux/uaccess.h> instead of <asm/uaccess.h>

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Cc: Andrew Victor <linux@maxim.org.za>
Cc: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>