Input: gpio-keys - use input_report_key()

Use the input_report_key() helper instead of open-coding the same
operation.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/185f3320e39000159d4bd843fd3119b94c30d607.1684854795.git.geert+renesas@glider.be


Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>