Fix for issue where rvfi_intr could have the wrong value after dummy instructions.

Created by: silabs-oysteink

Resetting 'dummy_suppressed_intr' if a new interrupt, nmi or exception is taken.

This fixes an issue in the following scenario:

1: Interrupt is taken, RVFI starts tracking in_trap (A) 2: The first interrupt handler is replaced by a dummy instruction, trap info (A) is stored in dummy_suppressed_intr 3: An NMI is taken before the original interrupt handler instruction retires. This 4: The first NMI handler instruction retires. This requires rvfi_trap to show the NMI, but dummy_suppressed_intr is used and trap info (A) is shown instead.