drm/etnaviv: don't move linear memory window on 3D cores without MC2.0

On cores with MC1.0 the memory window offset is not properly respected
by all engines in the core, leading to different views of the memory
if the offset in non-zero. This causes relocs for those engines to be
wrong and might lead to other subtile problems.

Rather than trying to work around this, just disable the linear memory
window offset for those cores.

Suggested-by: Russell King <linux@arm.linux.org.uk>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>