Input: bcm-keypad - remove unneeded NULL check before clk_disable_unprepare

clk_disable_unprepare() already checks NULL by using IS_ERR_OR_NULL.
Remove unneeded NULL check for kp->clk.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20220516085511.10679-1-wanjiabing@vivo.com


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