staging/rtl8192u: fixed typos

Fixed all checkpatch-warnings concerning typos in r8192U_core.c.

Signed-off-by: Yannik Schmidt <yannik.schmidt@thermoscan.de>
Signed-off-by: Lukas Lehnert <lukas.lehnert@web.de>
CC: linux-kernel@i4.cs.fau.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>