Update the interrupts vplan

Created by: silabs-robin

Updates the interrupts vplan that was previously copied over from 40P so that it now reflects features of the 40X.

Changelog:

General

• Moved items of the same feature adjacent to each other
• Updated "requirement location" to point to 40x user manual
• Added some minor comments on existing items
• (Hope I didn't ruin formatting, because excel defaults faught against the existing style used)
• Updated from "N/A" to "assertion coverage" for some assertion checks
• Cleanup up comments

Interrupt interface

• Removed "_o" suffix from irq_ack/irq_id (signals kept in rtl but not as top lvl pins)
• Added item about nmi and irq_ack
• Added item about rvfi_intr and irq_ack

Interrupt CSR

• Edited "MSTATUS MIE and MIE" to be clear, "MSTATUS[MIE] and MIE"

Interrupt instruction

• Removed Xpulp item
• Added all riscv extensions that are new in 40x contra 40p
• Updated wording of some "instructions interruped" items
• Added Zifencei item
• Added X interface instructions interrupted item
• Added illegal instructions interrupted item
• Removed "Counters" extension
• Added check that killed instructions have no side-effects

Eventually taken

• Added progress assertion for pending enabled interrupts

RVFI

• Added several items about rvfi interrupt signaling
• ...

NMI

• Added several items about nmi
• ...
• Added progress assertion for NMIs
• Added item for updating mstatus.mpie
• Updated mepc/mcause/mstatus items to check vs RM, instead of assertions
• Added item for nmip bit cover statement for debug/not