PROTO/RISC-V: origination PVM to use the protocol implementation

Closes of RV-320

What

Use the protocol implementation for riscv in the origination machine implementation as well

Why

Ensures consistency within the protocol and reduces code duplication when implementing the RISC-V PVM.

Manually testing the MR

Existing tezt rollup-node tests validates the change.

# Rollup node related tests
dune exec tezt/tests/main.exe -- --file sc_rollup.ml

# Riscv related tests
dune exec tezt/tests/main.exe -- --riscv              

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR