Input: xpad - move reporting xbox one home button to common function

[ Upstream commit 4f88476c75429ba9ab71c428b4cd2f67575bc9c1 ]

xbox one was the only device that has a *_process_buttons routine.

Signed-off-by: Pavel Rojtberg <rojtberg@gmail.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>