Staging: rtl8192u: make it compile

Add it to staging Kbuild and fixes some API differences that prevents
compilation.

It seems that the ieee80211 stack is very close to rtl8192su one.

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>