Delete utils/vpr_fixup_post_synth.py

[mithro]

The script at https://github.com/SymbiFlow/symbiflow-arch-defs/blob/master/utils/vpr_fixup_post_synth.py should not exist.

Instead either; (a) VPR should be fixed. (b) The simulators should be fixed.

We should not be doing work arounds like this when we can just fix things directly.

[mithro]

FYI - @kgugala