Staging: wlan-ng: block ioctls until card fully initialised

Add a mutex to block ioctls before the card is fully initialised and
only allow one ioctl at a time.
This stops udev trying to load the firmware before to card is fully up.

patch ported from wlan-ng-devel

Karl Relton <karllinuxtest.relton@ntlworld.com> spotted that this was
missing from the staging version,
http://lists.linux-wlan.com/pipermail/linux-wlan-devel/2009-February/003890.html

Signed-off-by: Richard Kennedy <richard@rsk.demon.co.uk>
Cc: Karl Relton <karllinuxtest.relton@ntlworld.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>