anv,iris: Port the D16 workaround stalls to BLORP
Commit cd401104 added stalls before register writes that occur when drivers emit depth stencil packets. However, it only did so for non-BLORP draw calls. Since those packets are sometimes emitted during BLORP calls, add stalls there too.
Closes: #4574 (closed)
Cc: mesa-stable
Edited by Nanley Chery