display: Relocate delayed_dpms_init_done() from plugins to core

display: Relocate delayed_dpms_init_done() from plugins to core

During display init, it is necessary to add a timer to wait for dpms initialization.
Also, that work should be handled in the display.c

Thus, this function is added below display.c
void display_add_timer_for_wating_dpms_init(void);
    -> This replaces add_timer_for_dpms_init()

Change-Id: Icfcc248b54899608a6a0c483df0ae572e0112798
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>