gpio: rcar: Propagate errors from devm_request_irq()

The driver overrides the error code returned by devm_request_irq() to
-ENOENT. Switch to propagating the error code upstream.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>