freedreno/ir3/ra: assign vreg names to all array elements

freedreno/ir3/ra: assign vreg names to all array elements

We shouldn't divide-by-two for half-reg arrays.  We set the proper node
interference class, based on `arr->half`.

Fixes a RA fail with 16b arrays:

  src/freedreno/ir3/ir3_ra.c:633: name_to_array: Assertion `!"invalid array name"' failed.

Caused by use/def iterators returning `arr->length` vreg namess, but
only assigning the array half that many names.

Also, since we are assigning unique vreg names to each array element,
there is no need to try and convert from half-reg to it's conflicting
full reg when pre-coloring the array elements.  Getting us closer to
having half-arrays work sanely with split-register-file (a5xx and
earlier).

Signed-off-by: Rob Clark <robdclark@chromium.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5957>