radv: set KEEP_TOGETHER_ENABLE if necessary on GFX10+

Ported from RadeonSI and PAL.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6838>
1 file changed