gpio: pca953x: do not ignore i2c errors

gpio: pca953x: do not ignore i2c errors

commit 540cffbab8b8e6c52a4121666ca18d6e94586ed2 upstream.

Per gpio_chip interface, error shall be proparated to the caller.

Attempt to silent diagnostics by returning zero (as written in the
comment) is plain wrong, because the zero return can be interpreted by
the caller as the gpio value.

Cc: stable@vger.kernel.org
Signed-off-by: Andrey Gusakov <andrey.gusakov@cogentembedded.com>
Signed-off-by: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>