gpio: pca954x: fix undefined error code from remove

gpio: pca954x: fix undefined error code from remove

The recent addition of the regulator support has led to the pca953x_remove
function returning uninitialized data when no platform data pointer is
provided, as gcc warns when using -Wmaybe-uninitialized:

drivers/gpio/gpio-pca953x.c: In function 'pca953x_remove':
drivers/gpio/gpio-pca953x.c:860:9: error: 'ret' may be used uninitialized in this function [-Werror=maybe-uninitialized]

This restores the previous behavior, returning 0 on success.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: e23efa311110 ("gpio: pca954x: Add vcc regulator and enable it")
Acked-by: Phil Reid <preid@electromag.com.au>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>