freedreno/ir3/cf: skip array load/store

freedreno/ir3/cf: skip array load/store

Don't fold conversions into array (incl phi lowered to regs/array).
These aren't SSA.  Avoids crashes in particular in frag shaders with
flow control, which would leave a dangling array write disconnect from
the original cov src.

Possibly this could be slightly relaxed, if there is no other consumer
of the src, and it were in the same block.  But it would require
updating block->keeps, and taking care of barrier state.  Which isn't a
thing the cf pass does currently.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4423>