ir3: Convert to register intrinsics
What does this MR do and why?
ir3: Convert to register intrinsics
Thanks to our SSA-based RA, we only use nir_register for arrays, and we only access array registers with dedicated moves anyway. So there's no reason to need any fancy coalescing... we can just switch to register access intrinsics and translate them to moves exactly like we would've done when getting srcs/dests before.
This addresses the ir3 portion of #9051 (closed).
No shader-db changes with a (significant subset of) Rob's shader-db. (Some shaders are affected by this change but not in any way that shows up in the stats.)