drm/etnaviv: get cmdbuf physical address through the cmdbuf abstraction

Don't allow IOMMUv2 to peek directly into the cmdbuf, but get the
needed PA through a dedicated function.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>
4 files changed