panfrost: Zero tripipe on initialize

I don't think the hardware cares, but this adds a lot of noise to traces
that we would rather not need to look at.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>

src/gallium/drivers/panfrost/pan_context.c

@@ -2120,7 +2120,7 @@ panfrost_bind_shader_state(
                         }
                 }
 
-                variants->variants[variant].tripipe = malloc(sizeof(struct mali_shader_meta));
+                variants->variants[variant].tripipe = calloc(1, sizeof(struct mali_shader_meta));
 
         }