Input: mtk-pmic-keys - use single update when configuring long press behavior

Instead of doing 3 read-modify-write operations when configuring behavior
of long-press, consolidate everything into one.

Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com> # on mt8183-pumpkin
Link: https://lore.kernel.org/r/YowH0Q5HAGU7Grx2@google.com


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