Staging: arlan: delete the driver

It has sat in the staging directory since October of 2009, and no one
has stepped up to take it over, so odds are, no one cares about it
anymore.  So, it is now deleted as scheduled, and documented in the TODO
file.

Cc: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>