pan/mdg: Print constant vectors less wrong

For !32-bit types, we need to pay attention to rep_low/high/half to
determine the effective swizzle.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5151>
1 file changed