Fix VLSI input files list emission to avoid bash "too many arguments" error

[sagark]

This makes the expansion of "cat $(VLSI_RTL)" happen as a child of the shell that runs the for loop.

The existing version will sometimes produce a bash "too many arguments" error because the

$(shell cat $(VLSI_RTL)) 

is expanded first and then passed as a giant command to bash.

• Bug fix
• New feature
• Other enhancement

Impact:

• RTL change
• Software change (RISC-V software)
• Build system change
• Other

Contributor Checklist:

• Did you set main as the base branch?
• Is this PR's title suitable for inclusion in the changelog and have you added a changelog:<topic> label?
• Did you state the type-of-change/impact?
• Did you delete any extraneous prints/debugging code?
• Did you mark the PR with a changelog: label?

[harrisonliew]

Ah, is now a problem due to CIRCT, eh?
Can you also change this in power.mk and sim.mk?