display: Move display blink functions from plugin to core display module

display: Move display blink functions from plugin to core display module

Remove and redefine display blink functions.
These functions are added to below display-backlight.

void display_backlight_set_blink(int timeout)
-> This function set display blink behavior by adding timeout callback.
void display_backlight_unset_blink(void)
-> This function remove blink callback function after DUMP_MODE_WAITING_TIME time.

Change-Id: Iafe293ff9ff8ad65b971885bfd949e037bcffa40
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>