drm/etnaviv: don't disable TS on MMUv2 core when moving the linear window

On MMUv2 cores the linear window is only relevant when starting the FE,
before the MMU has been activated. Once the MMU is active, all accesses
are translated with no way to bypass the MMU via the linear window. Thus
TS ignoring the linear window offset is not an issue on cores with MMUv2
present and there is no need to disable TS when we need to move the
linear window.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Tested-by: Joao Paulo Goncalves <joao.goncalves@toradex.com>