Input: gpio_keys - defer probing if GPIO probing is deferred

Input: gpio_keys - defer probing if GPIO probing is deferred

commit e324ce61ef483dd26d03502d35666ad48a2e1b33 upstream.

If of_get_gpio_flags() returns an error (as in case when GPIO probe is
deferred) the driver would attempt to claim invalid GPIO. It should
propagate the error code up the stack instead so that the probe either
fails or will be retried later (in case of -EPROBE_DEFER).

Reported-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>