panfrost/midgard: Prettify embedded constant prints

panfrost/midgard: Prettify embedded constant prints

Until now, embedded constants were printed as all 32 bits integer or
floats, but the compiler can pack constant from different types if
severa instructions with different reg_mode and native type refer to
the constant register. Let's implement something smarter so users don't
have to do a manual conversion when looking at a trace.

Note that 8-bit constants are not decoded yet, as we're not sure how
the writemask is encoded in that case.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3536>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3536>