Input: gpio_keys_polled - defer probing if GPIO probing is deferred

Input: gpio_keys_polled - defer probing if GPIO probing is deferred

commit d46329a708c1a3301e272a029266b69339c0877f upstream.

If GPIO probing is deferred, the driver tries to claim an invalid GPIO line
which leads to an error message like this:

  gpio-keys-polled buttons.2: unable to claim gpio 4294966779, err=-22
  gpio-keys-polled: probe of buttons.2 failed with error -22

We should make sure that error code returned by of_get_gpio_flags (including
-EPROBE_DEFER) is propagated up the stack.

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