media: usbvision: remove unneeded DRIVER_LICENSE #define

There is no need to #define the license of the driver, just put it in
the MODULE_LICENSE() line directly as a text string.

This allows tools that check that the module license matches the source
code license to work properly, as there is no need to unwind the
unneeded dereference.

Cc: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Johan Hovold <johan@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
Reported-by: Philippe Ombredanne <pombredanne@nexb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Acked-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>