i965/gen9: Enable KHR_texture_compression_astc_sliced_3d

Signed-off-by: Anuj Phogat <anuj.phogat@gmail.com>
Reviewed-by: Nanley Chery <nanley.g.chery@intel.com>

src/mesa/drivers/dri/i965/intel_extensions.c

@@ -391,6 +391,7 @@ intelInitExtensions(struct gl_context *ctx)
 
    if (brw->gen >= 9) {
       ctx->Extensions.KHR_texture_compression_astc_ldr = true;
+      ctx->Extensions.KHR_texture_compression_astc_sliced_3d = true;
       ctx->Extensions.ARB_shader_stencil_export = true;
    }