Staging: rtl8723bs: remove useless structs in rtw_io.h

Remove the following unreferenced struct's in include/rtw_io.h:

	struct reg_protocol_rd
	struct reg_protocol_wt

Signed-off-by: Marco Cesati <marcocesati@gmail.com>
Link: https://lore.kernel.org/r/20210322133717.17797-14-marcocesati@gmail.com


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