staging: rtl8723bs: Remove function rtw_btcoex_GetDBG()

Remove function rtw_btcoex_GetDBG as all it does is call
hal_btcoex_GetDBG.
Modify call site accordingly.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190702070132.6997-7-nishkadg.linux@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>