Input: da9063 - report KEY_POWER instead of KEY_SLEEP during power key-press

Stop reporting KEY_SLEEP for a short key-press and report KEY_POWER instead
This change applies to both DA9063 and DA9062 ONKEY drivers.

A previous application used for testing by the developer required a
KEY_SLEEP and KEY_POWER input_report_key event to distinguish between a
short and long key-press of the power key.  This is not the general
convention and the typical solution is for KEY_POWER to be used in both
cases: suspend and S/W power off.

Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>