xfree86: Bump ABI_VIDEODRV_VERSION to 25.2

This gives out of tree drivers a fighting chance to build against both
sides of
xorg/xserver!468 .

Reviewed-by: Dave Airlie <airlied@redhat.com>
4 jobs for ABI_VIDEODRV_VERSION-25.2 in 3 minutes and 42 seconds (queued for 1 second)
Status Job ID Name Coverage
  Docker Image
passed #3573195
debian-testing

00:00:22

 
  Build And Test
passed #3573196
autotools

00:03:19

passed #3573197
meson

00:01:06

passed #3573198
meson-noglamor

00:01:16