anv/iris: Drop depth cache flush requirement after depth clear/resolve on Gfx 12+
What does this MR do and why?
From Bspec 46959, a programming note:
Since HZ_OP has to be sent twice (first time set the clear/resolve
state and 2nd time to clear the state), and HW internally flushes the
depth cache on HZ_OP, there is no need to explicitly send a Depth
Cache flush after Clear or Resolve.