XIF needs access to mstatus

Created by: Silabs-ArjanB

The vector spec states:

• Attempts to execute any vector instruction, or to access the vector CSRs, raise an illegal-instruction exception when mstatus.VS is set to Off.
• When mstatus.VS is set to Initial or Clean, executing any instruction that changes vector state, including the vector CSRs, will change mstatus.VS to Dirty.

Therefore mstatus needs to become part of the XIF protocol (e.g. part of the issue/result interface)

A similar requirement exists for the FPU