staging: rtl8188eu: Fixed a space coding style issue.

Fixed a space coding style issue which was found when running checkpatch.pl
script on rtw_ap.c.

Signed-off-by: Gangadhar Vukkesala <gangs.freelancer@gmail.com>
Reviewed-by: Jeremiah Mahler <jmmahler@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>