display: Move white_balance_ops functions from plugins to core display module

display: Move white_balance_ops functions from plugins to core display module

Remove and redefine functions related to display white balance work.
Because white balancing is common for display.
Thus, these functions are added below display-panel.

int display_panel_set_white_balance(enum hal_display_white_balance white_balance_type, int value)
int display_panel_get_white_balance(enum hal_display_white_balance white_balance_type, int* out_val)
-> With hal_display_white_balance enum type, it is possible to get and set white_balance values.

Change-Id: I10213315d109e47f0e8c3a58382648ccef3ca2d1
Signed-off-by: Yunhee Seo <yuni.seo@samsung.com>