Input: pxa27x_keypad bug fix for direct_key_mask

When direcct_key_num is 0, the mask should be 0.
When direcct_key_num is 1, the mask should be 0b1.
Signed-off-by: Chao Xie <chao.xie@marvell.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>

drivers/input/keyboard/pxa27x_keypad.c

@@ -383,7 +383,7 @@ static void pxa27x_keypad_config(struct pxa27x_keypad *keypad)
 	if (pdata->direct_key_num > direct_key_num)
 		direct_key_num = pdata->direct_key_num;
 
-	keypad->direct_key_mask = ((2 << direct_key_num) - 1) & ~mask;
+	keypad->direct_key_mask = ((1 << direct_key_num) - 1) & ~mask;
 
 	/* enable direct key */
 	if (direct_key_num)