display: Relocate update_setting() from plugins to core

display: Relocate update_setting() from plugins to core

update_setting() is called from display init() and it updates pm related setting.
Actually, this function does a lot of work according to the incoming key value.
Also, it is necessary to change the initialization way, so it will be refactored after relocation.

To relocate, wrapper functions are added below display-plugin.
- bool display_plugin_is_there_update_pm_setting(void);
- int display_plugin_is_lcd_on_blocked(void);
- int display_plugin_set_power_save_mode_flag(int onoff);
    -> This wrapper is added for wearable plugin.

New function is added below display/setting
- int display_setting_update_pm_setting(int key_idx, int val);
    -> This is temporary function, it will be refactored.

Change-Id: I90564168f72df733e887e231fa8262a7a83f86ac
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>