Staging: wlan-ng: Change KERN_DEBUG or pr_debug to match orig driver

Change uses of KERN_DEBUG over to pr_debug to match original driver
where messages are only needed during driver development.

Signed-off-by: Karl Relton <karllinuxtest.relton@ntlworld.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>