By default all files without license information are under the default
license of the kernel, which is GPL version 2.  Because of this, add the
GPL-2.0 identifier to the quatec_daqp_cs driver which did not have any license
identifiers in it at all.

Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: Brent Baccala <baccala@freesoft.org>
Cc: David A. Schleef <ds@schleef.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>