rtlwifi: btcoexist: Modify driver to support BT coexistence in rtl8723be

This patch adds the routines found in the V062814 Realtek version.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: troy_tan@realsil.com.cn
Signed-off-by: John W. Linville <linville@tuxdriver.com>