mesa: update to version 25.2.4

mesa: update to version 25.2.4

Mesa 25.2 brings a bunch of new features, especially the Panfrost Vulkan
driver saw many improvements.

See https://docs.mesa3d.org/relnotes.html for details about what has
happened since Mesa 25.1.6.

Note that OSMesa as well as the old OpenCL 1.1 support has been dropped.
The new Rusticl OpenCL implementation cannot be supported yet as OpenWrt's
meson integration still lacks support for Rust at this point.

Signed-off-by: Daniel Golle <[email protected]>