display: Remove battery plugin using from display plugin

display: Remove battery plugin using from display plugin

display plugin used get_charging_status() from initialization steps.
To use that function, display plugin loaded battery plugin.
However, that function is not exist in the battery plugin.
Thus, that function loading and accessing is useless work.

Also, loading battery plugin from the display plugin structure should be removed.

This function is added to display-misc.
- void display_misc_set_battery_charging_status_flag(void);
    -> It checks battery charging status and sets CHRGR_FLAG.
    -> This function should be relocated during battery plugin refactoring.

Change-Id: I943768785b654a660982a3017cafd0e41b7b94ed
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>