Input: ep93xx_keypad - prepare clock before using it

Use clk_prepare_enable()/clk_disable_unprepare() in preparation for switch
to Common Clock Framework.

Signed-off-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20210613233041.128961-4-alexander.sverdlin@gmail.com


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