Staging: rtl8192u: Convert comments from C99 to C89 style

Kernel style for comments is C89 style. Issue found by checkpatch.pl.

Signed-off-by: Ksenija Stanojevic <ksenija.stanojevic@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>