Staging: rtl8187se: Fix C99 style commenting in dot11d.c

This patch fixes the following checkpatch.pl issues in
ieee80211/dot11d.c-
ERROR: do not use C99 // comments

Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>