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

commit 53f8d322 upstream.

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.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/gpio/gpio-pca953x.c

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