staging: wlan-ng: remove unnecessary out of memory message in p80211conv.c

This patch fix the following checkpatch script warning:
WARNING: Possible unnecessary 'out of memory' message.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>