staging: rtl8723au: Pass a struct rtw_adapter * to the USB functions

This lowers the dependency on struct intf_hdl so we can start getting
rid of if.

Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>