Specify how the commit handshake should be interpreted when an instruction is not accepted by a coprocessor

Created by: Silabs-ArjanB

Even if a coprocessor does not accept a specific offloaded instruction, then the CPU still has to provide a related handshake over the commit interface. It should be stated that the coprocessor will receive this handshake, but that it can ignore the value of commit_kill (as from the coprocessor's point of view there is no offloaded instruction to commit or kill). This prevents a combinatorial path from the issue response (accept) to the commit interface.