[dv] Add flag needed to allow force under VCS

Tests targetting security features make use of force to corrupt values.
Under VCS this requires building with a particular flag.

dv/uvm/core_ibex/yaml/rtl_simulation.yaml

@@ -39,6 +39,7 @@
           -xlrm uniq_prior_final
           -CFLAGS '--std=c99 -fno-extended-identifiers'
           -lca -kdb
+          -debug_access+f
           <cmp_opts> <wave_opts> <cov_opts> <cosim_opts>
     cov_opts: >-
       -cm line+tgl+assert+fsm+branch