ZTS: pool_state test check for pool existence in cleanup

If there is no scsi_debug module, then this test
must be skipped, in this case cleanup routine should
be prepared for absent pool.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: George Melikov <mail@gmelikov.ru>
Closes #11534

tests/zfs-tests/tests/functional/procfs/pool_state.ksh

@@ -61,6 +61,7 @@ function cleanup
 			log_must rm -f $BACKUP
 		fi
 
+		if poolexists $TESTPOOL2 ; then
 			# Our disk is back.  Now we can clear errors and destroy the
 			# pool cleanly.
 			log_must zpool clear $TESTPOOL2
@@ -70,7 +71,8 @@ function cleanup
 			wait
 
 			destroy_pool $TESTPOOL2
-		log_must rm $REALDISK
+		fi
+		log_must rm -f $REALDISK
 		unload_scsi_debug
 	fi
 }