ir3: Don't pack FS inlocs
What does this MR do and why?
ir3: Don't pack FS inlocs
Thanks to transform feedback, we don't know which varying components
will be used when compiling the FS. The VS could use additional
components for xfb, and packing the inlocs per-component would result in
overlapping varyings. In order to do this properly, we'd need to create
a variant for the FS when used with xfb.