Input: mt6779-keypad - add MediaTek keypad driver

Input: mt6779-keypad - add MediaTek keypad driver

This patch adds matrix keypad support for Mediatek SoCs.

Signed-off-by: fengping.yu <fengping.yu@mediatek.com>
Reviewed-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Link: https://lore.kernel.org/r/20220303154302.252041-3-mkorpershoek@baylibre.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>