vallium: disable VK_KHR_shader_float16_int8.

This is actually a TODO.

Fixes:
dEQP-VK.info.device_mandatory_features

Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6381>
diff --git a/src/gallium/frontends/vallium/val_extensions.py b/src/gallium/frontends/vallium/val_extensions.py
index 905d38b..bb6cacf 100644
--- a/src/gallium/frontends/vallium/val_extensions.py
+++ b/src/gallium/frontends/vallium/val_extensions.py
@@ -93,7 +93,7 @@
     Extension('VK_KHR_sampler_ycbcr_conversion',          1, False),
     Extension('VK_KHR_shader_atomic_int64',               1, False),
     Extension('VK_KHR_shader_draw_parameters',            1, False),
-    Extension('VK_KHR_shader_float16_int8',               1, True),
+    Extension('VK_KHR_shader_float16_int8',               1, False),
     Extension('VK_KHR_storage_buffer_storage_class',      1, True),
     Extension('VK_KHR_surface',                          25, 'VAL_HAS_SURFACE'),
     Extension('VK_KHR_surface_protected_capabilities',    1, 'VAL_HAS_SURFACE'),