etnaviv: disable linear PE by default

etnaviv: disable linear PE by default

Linear PE causes a lot of issues in the ZS stage. While some of those issues
can be worked around on newer GPU cores by doing all ZS operations in the
late stage, GC600 r4653 exhibits spurious Z fails when linear PE is active
even though this GPU does not even have a early Z stage.

Disable linear PE for now, until the issue can be analyzed further. Leave the
debug option in place to allow to enable linear PE for testing.

Fixes: 43eb5e777e4b ("etnaviv: add debug option to disable linear PE feature")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/20405>