intel/brw: Pull emit_dummy_memory_fence_before_eot out of fs_visitor

Rename to workaround_memory_fence_before_eot and return the already
present progress value for consistency.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26887>
2 files changed