drm/etnaviv: add clock gating workaround for GC7000 r6202

The LS1028A SoC errata sheet mentions A-050121 "GPU hangs if clock
gating for Rasterizer, Setup Engine and Texture Engine are enabled".
The workaround is to disable the corresponding clock gatings.

Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>