Remove the layout argument of [free_block].

This information is already contained in the allocation map. Removing
makes it easier to relate to the Cerberus memory model interface.
2 jobs for ci/free_no_layout in 21 minutes and 29 seconds (queued for 2 seconds)
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Status Name Job ID Coverage
  Build
passed build-coq.8.12.0 #128710
fp

00:21:29

passed check-generated #128711
fp

00:07:50