We have a situation in some skia shaders like:
add.f r0.x, ...
(rpt2)nop
mul.f ..., r0.x
sam (xyzw) r0.x, ...
rcp ..., r0.x
Notice that rcp uses the result of the sam instruction, not the add.f,
but we didn't keep track of which instructions kill the sources in
ir3_delay, so we'd add an extra nop, resulting in a disagreement betwen
ir3_delay and the scheduling graph. Since postsched is correct, fix
ir3_delay. This only results in some very slight shader-db changes but
keeps the next commit from changing things.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13722>