panfrost: Allow up to 16 UBOs

This is the hardware max, as far as I can tell.

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

src/gallium/drivers/panfrost/pan_screen.c

@@ -319,7 +319,7 @@ panfrost_get_shader_param(struct pipe_screen *screen,
                 return 16 * 1024 * sizeof(float);
 
         case PIPE_SHADER_CAP_MAX_CONST_BUFFERS:
-                return 4;
+                return 16;
 
         case PIPE_SHADER_CAP_TGSI_CONT_SUPPORTED:
                 return 0;