devicectl: add suspend/resume command

devicectl: add suspend/resume command

Usage: devicectl power suspend|resume reason(int)
 #) devicectl power suspend 12345
 #) devicectl power resume 2000

The value reason can be an any integer and the devicectl doesn't test
it is valid reason or not. Therefore some listeners of suspend/resume
event might malfunction as they receive a wierd reason.

Change-Id: I62c66e0a8034f9884fd006404991330902ecca21
Signed-off-by: Youngjae Cho <y0.cho@samsung.com>
(cherry picked from commit 4d0daf18b56643cfaeb81f7ca777135726340398)