v3dv: amend tile size tables with smallest tile sizes available

We'll need this for some cases involving maximum number of multisampled
color targets.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6766>

src/broadcom/vulkan/v3dv_cmd_buffer.c

@@ -473,6 +473,8 @@ job_compute_frame_tiling(struct v3dv_job *job,
       32, 32,
       32, 16,
       16, 16,
+      16,  8,
+       8,  8
    };
 
    assert(job);

src/broadcom/vulkan/v3dv_pass.c

@@ -234,6 +234,8 @@ v3dv_subpass_get_granularity(struct v3dv_render_pass *pass,
       32, 32,
       32, 16,
       16, 16,
+      16,  8,
+       8,  8
    };
 
    /* Our tile size depends on the number of color attachments and the maximum