meson: Remove panfrost from default driver list

Until the kernel side matures and the full driver is upstreamed, to
avoid end-user surprises, Panfrost should only be built for the
adventurous.

Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Reviewed-by: Eric Anholt <eric@anholt.net>

meson.build

@@ -132,7 +132,7 @@ if _drivers.contains('auto')
     elif ['arm', 'aarch64'].contains(host_machine.cpu_family())
       _drivers = [
         'kmsro', 'v3d', 'vc4', 'freedreno', 'etnaviv', 'nouveau',
-        'tegra', 'virgl', 'swrast', 'panfrost'
+        'tegra', 'virgl', 'swrast'
       ]
     else
       error('Unknown architecture @0@. Please pass -Dgallium-drivers to set driver options. Patches gladly accepted to fix this.'.format(