[cv32e40p] make file updates and minor updates for riscof setup

Created by: dd-vaibhavjain

This PR includes:

• fix for open action item for vcs.mk #2018 (closed)

• add new clean_test target in make files for just removing given test(left clean target untouched), improve clean_all

• update riscof plugin and related make targets for minor improvements, enable iss and coverage.

• update for fix from riscv_arch_test suite for mtvec align

• add 2 regress lists for these riscv_arch_test

• Add support for additional runtime plusargs passed from a separate yaml file in test_cfg/ dir

• Use the test_cfg yaml as additional "test configuration" to build the test simulation run dir paths, log names, coverage db name.

• add 2 test_cfg yaml

• Fix for Imperas coverage defines name change