Staging: comedi: Add MODULE_LICENSE and similar to NI modules

As mentioned by W. Trevor King on the devel@linuxdriverproject.org list
on "Thu, 27 Jan 2011 18:52:15 -0500", "Message-ID:
<20110127235214.GA5107@thialfi.dhcp.drexel.edu>", the ni_pcimio module
is missing module metadata, including a license.

This patch adds module metadata to all the NI comedi driver modules.  It
also removes a duplicate MODULE_LICENSE("GPL") line from the "mite"
module.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Cc: W. Trevor King <wking@drexel.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>