ir3: do not move varying inputs that depend on unmovable instrs

ir3: do not move varying inputs that depend on unmovable instrs

Not all varying fetches could be pulled into the start block.
If there are fetches we couldn't pull, like load_interpolated_input
with offset which depends on a non-reorderable ssbo load or on a
phi node, this pass is skipped since it would be hard to find a place
to set (ei) flag (beside at the very end).

We also don't have to manually set (ei) in such cases since a5xx and
a6xx do automatically release varying storage at the end.
Earlier gens need further testing, however they do not support
interpolateAt* functions at moment, so unless we would like to support
sample shading on them - they are fine.

Fixes crash in GTA V.

Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10483>