Input: nomadik-ske-keypad - provide some missing struct member docs

Input: nomadik-ske-keypad - provide some missing struct member docs

Fixes the following W=1 kernel build warning(s):

 drivers/input/keyboard/nomadik-ske-keypad.c:71: warning: Function parameter or member 'pclk' not described in 'ske_keypad'
 drivers/input/keyboard/nomadik-ske-keypad.c:71: warning: Function parameter or member 'ske_keypad_lock' not described in 'ske_keypad'

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20201104162427.2984742-20-lee.jones@linaro.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>