radeonsi: disable CE by default

radeonsi: disable CE by default

It makes performance worse by a very small (hard to measure) amount.
We've done extensive profiling of this feature internally.

Cc: 17.1 17.2 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Acked-by: Christian König <christian.koenig@amd.com>
(cherry picked from commit 1ab7fed7079a8b0f670d6a51ddc98691ace29508)
[Andres Gomez: resolve trivial conflicts]
Signed-off-by: Andres Gomez <agomez@igalia.com>
Conflicts:
	src/gallium/drivers/radeonsi/si_pipe.c