gpio: ws16c48: Mask read inputs for get_multiple

This patch masks the read inputs with the word mask in order to ensure
only requested input states are returned in the bits array.
Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-ws16c48.c

@@ -169,7 +169,7 @@ static int ws16c48_gpio_get_multiple(struct gpio_chip *chip,
 		port_state = inb(ws16c48gpio->base + i);
 
 		/* store acquired bits at respective bits array offset */
-		bits[word_index] |= port_state << word_offset;
+		bits[word_index] |= (port_state << word_offset) & word_mask;
 	}
 
 	return 0;