gpio / ACPI: fix returned error from acpi_dev_gpio_irq_get()

acpi_dev_gpio_irq_get() currently ignores the error returned
by acpi_get_gpiod_by_index() and overwrites it with -ENOENT.

Problem is this error can be -EPROBE_DEFER, which just blows
up some drivers when the module ordering is not correct.

Cc: stable@vger.kernel.org
Signed-off-by: David Arcari <darcari@redhat.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>