rar: Fix off by one error

It looks like there is an off-by-one error in one of your changes to
drivers/staging/rar_register/rar_register.c:
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/platform/x86/intel_rar_register.c

@@ -145,7 +145,7 @@ static void free_rar_device(struct rar_device *rar)
  */
 static struct rar_device *_rar_to_device(int rar, int *off)
 {
-	if (rar >= 0 && rar <= 3) {
+	if (rar >= 0 && rar < MRST_NUM_RAR) {
 		*off = rar;
 		return &my_rar_device;
 	}