pan/midgard: Rewrite bidirectionally when eliminating moves

pan/midgard: Rewrite bidirectionally when eliminating moves

Symptom: the sky is black in SuperTuxKart (flashbacks to SMB/NES
emulation intensify).

Essentially, what happened is a fixed (special) move to r0 was
eliminated but scheduling did not factor this in, so
can_run_concurrent_ssa returned true even when there was a logical data
dependency that needed to be resolved.

Fixes: 20771ede1c0 ("pan/midgard: Add post-RA move elimination")
Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>