Input: gpio_keys_polled - convert to devm-* API

Replace existing resource handling in the driver with managed device
resources, this ensures more consistent error values and simplifies error
handling paths:

kzalloc -> devm_kzalloc
gpio_request_one -> devm_gpio_request_one
input_allocate_polled_device -> devm_input_allocate_polled_device

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>