etnaviv: remove stale comment in etna_resource_copy_region

The comment about using the RS engine was correct before the code got
changed to use the 3D blitter and a fallback before etnaviv was merged
into upstream Mesa. It has been incorrect ever since. As it's just
adding confusion, instead of being helpful, remove it.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/9310>

src/gallium/drivers/etnaviv/etnaviv_clear_blit.c

@@ -156,15 +156,6 @@ etna_resource_copy_region(struct pipe_context *pctx, struct pipe_resource *dst,
 {
    struct etna_context *ctx = etna_context(pctx);
 
-   /* XXX we can use the RS as a literal copy engine here
-    * the only complexity is tiling; the size of the boxes needs to be aligned
-    * to the tile size
-    * how to handle the case where a resource is copied from/to a non-aligned
-    * position?
-    * from non-aligned: can fall back to rendering-based copy?
-    * to non-aligned: can fall back to rendering-based copy?
-    * XXX this goes wrong when source surface is supertiled.
-    */
    if (src->target != PIPE_BUFFER && dst->target != PIPE_BUFFER &&
        util_blitter_is_copy_supported(ctx->blitter, dst, src)) {
       etna_blit_save_state(ctx);