tests: Exit riscv_asmtest script with simulator status code (#891)

It will be helpful to check if the instruction simulate well

Change-Id: I5faa435fad79601682126ee7978d8444093df900

tests/gem5/asmtest/configs/riscv_asmtest.py

@@ -32,6 +32,7 @@ gem5 while still being functinal.
 """
 
 import argparse
+import sys
 
 from gem5.components.boards.simple_board import SimpleBoard
 from gem5.components.cachehierarchies.classic.no_cache import NoCache
@@ -119,3 +120,5 @@ print(
         simulator.get_current_tick(), simulator.get_last_exit_event_cause()
     )
 )
+
+sys.exit(simulator.get_last_exit_event_code())