Input: mcs-touchkey - convert to use devm_* api

Use devm_* api to simplify code, this makes it unnecessary to explicitly
release resources.

Signed-off-by: Yangtao Li <frank.li@vivo.com>
Link: https://lore.kernel.org/r/20230714080611.81302-3-frank.li@vivo.com


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