Use gpio_is_valid instead of assuming that every GPIO
number != 0 is valid while 0 is not.
Signed-off-by: NPhilipp Zabel <philipp.zabel@gmail.com>
Acked-by: NEric Miao <eric.y.miao@gmail.com>
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>