staging: fix go7007-usb license

Add MODULE_LICENSE() for this source module to fix build warning:

WARNING: modpost: missing MODULE_LICENSE() in drivers/staging/media/go7007/go7007-usb.o
see include/linux/module.h for more information

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: Ross Cohen <rcohen@snurgle.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>