gpio: pca953x: Fix corruption of other gpios in set_multiple.

gpiod_set_array_value_complex does not clear the bits field.
Therefore when the drivers set_multiple funciton is called bits outside
the mask are undefined and can be either set or not. So bank_val needs
to be masked with bank_mask before or with the reg_val cache.

Cc: stable@vger.kernel.org
Fixes: b4818afe ("gpio: pca953x: Add set_multiple to allow multiple")
Signed-off-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-pca953x.c

@@ -380,6 +380,7 @@ static void pca953x_gpio_set_multiple(struct gpio_chip *gc,
 		if (bank_mask) {
 			bank_val = bits[bank / sizeof(*bits)] >>
 				  ((bank % sizeof(*bits)) * 8);
+			bank_val &= bank_mask;
 			reg_val[bank] = (reg_val[bank] & ~bank_mask) | bank_val;
 		}
 	}