staging: rtl8723bs: Remove rtw_btcoex_IsBTCoexCtrlAMPDUSize()

Remove function rtw_btcoex_IsBTCoexCtrlAMPDUSize as it does nothing
except call hal_btcoex_IsBTCoexCtrlAMPDUSize.
Modify call site accordingly.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Link: https://lore.kernel.org/r/20190702070132.6997-5-nishkadg.linux@gmail.com


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