anv: Don't use clflush for discrete GPUs
What does this MR do and why?
anv: Don't use clflush for discrete GPUs
intel_clflush_range isn't defined on arm64, so this fixes the anv build on arm64.
Fixes: 521c216e ("anv: use COMPUTE_WALKER post sync field to track compute work") Signed-off-by: Alyssa Rosenzweig alyssa@rosenzweig.io