drm/msm/a6xx: add missing PC_DBG_ECO_CNTL bit for a640/a650

See downstream's "disable_tseskip" flag.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Link: https://lore.kernel.org/r/20210608172808.11803-5-jonathan@marek.ca


Signed-off-by: Rob Clark <robdclark@chromium.org>