check: unmount TEST_DEV and SCRATCH_DEV after test run

Unmount TEST_DEV and SCRATCH_DEV after each test run to avoid
mounting multiple devices on the same mount point which might result
in xfstest not being able to unmount the device later down the path.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

check

@@ -620,6 +620,9 @@ for section in $HOST_OPTIONS_SECTIONS; do
 	done
 	_wrapup
 	echo
+
+	umount $TEST_DEV 2> /dev/null
+	umount $SCRATCH_DEV 2> /dev/null
 done
 
 interrupt=false