pan/va: Print instructions with pack assert fails

pan/va: Print instructions with pack assert fails

va_pack asserts a large number of invariants about the instruction being packed.
If one of these fails (due to an invalid instruction), it's helpful to inspect
the failing instruction, as it may not be apparent in a large shader. Pass the
instruction through with all the assertions in va_pack for easier debugging.

Now assertion failures when packing are easier to debug:

   Invalid invariant lo.type == hi.type:
       = STORE.i32.flow2.wls br5, br2, wls_ptr[1], byte_offset:0

Signed-off-by: Alyssa Rosenzweig <alyssa@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/17224>