add initial b extension support (!823) · Merge requests · OpenHW Group / backup-20241120 / core-v-verif

Created by: strichmo

ISACOV model updated based on reviews for A B and C extensions
basic support for the B extension added including a directed test (Note that this will require a toolchain with experimental B support. The default is no B extension.)
rework the derivation of MARCH in all firmware and bsp builds for uvmt testbench. This may require communication as usage has changed (and a review).

This PR passed a DSIM regression with cv32e40x rel check and cv32e40p ci check

add initial b extension support