staging: wlan-ng: fix block comment warnings in prism2mgmt.c

This patch fix the following checkpatch.pl warnings in prism2mgmt.c:
WARNING: Block comments should align the * on each line
WARNING: Block comments use a trailing */ on a separate line
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>