staging: r8188eu: attach newly imported driver to build system

Modify Kconfig and Makefile to import new r8188eu driver into build
system, and allow it to build alongside deprecated older driver, by
tweaking build parameters and module name for the older driver at
the same time.

Suggested-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Phillip Potter <phil@philpotter.co.uk>
Link: https://lore.kernel.org/r/20210727232219.2948-7-phil@philpotter.co.uk


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