pan/mdg: Fix spilling of non-32-bit types

The source argument for mov has index 1, not 0.

Fixes a vertex shader in SuperTuxKart.

Fixes: b4de9e035ac ("pan/mdg: Mask spills from texture write")
Reported-by: macc24
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>~
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6659>
1 file changed