HID: wacom: Replace __set_bit with input_set_capability

It's a trivial patch. It's doesn't change the functionality as the helper
input_set_capability does the same thing.

Signed-off-by: Przemo Firszt <przemo@firszt.eu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-wacom.c b/drivers/hid/hid-wacom.c
index f9af474..3fc9386 100644
--- a/drivers/hid/hid-wacom.c
+++ b/drivers/hid/hid-wacom.c
@@ -492,9 +492,7 @@
 	__set_bit(BTN_MIDDLE, input->keybit);
 
 	/* Pad */
-	input->evbit[0] |= BIT(EV_MSC);
-
-	__set_bit(MSC_SERIAL, input->mscbit);
+	input_set_capability(input, EV_MSC, MSC_SERIAL);
 
 	__set_bit(BTN_0, input->keybit);
 	__set_bit(BTN_1, input->keybit);