gpio: gpio-mm: 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 <[e-mail]>
Signed-off-by: William Breathitt Gray <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-gpio-mm.c

···
 		port_state = inb(gpiommgpio->base + ports[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;