package/kodi-screensaver-rsxs: switch license to GPL-2.0+

package/kodi-screensaver-rsxs: switch license to GPL-2.0+

Upstream commit
https://github.com/xbmc/screensavers.rsxs/commit/dbb88536964dc0ca4144016eb12f7307b60cb1fa

removed lib/rsxs-1.0 which was licensed as GPL-3.0.

During the latest version bump
https://git.buildroot.net/buildroot/commit/package/kodi-screensaver-rsxs?id=e68bcc985fbb17e50cfa2944807090b6cd57c871

KODI_SCREENSAVER_RSXS_LICENSE_FILES = lib/rsxs-1.0/COPYING

was removed but the corresponding license change was forgotton.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>