staging: r8188eu: move struct rt_firmware to rtw_fw.h

Move the rt_firmware structure to the header rtw_fw.h to have firmware
related things in one place.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220407192819.10661-3-straube.linux@gmail.com


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