Fix help string for f2fs

Help showed the operands in the wrong order. The script does not appear
to allow for there to be in different order, so fixing the help message

Test: None (could confirm necessary by invoking with flags in other
      order and seeing that it doesn't see the flags)

Change-Id: Ia0a5a41f4743caf03e39df7be53f717a2642b764
1 file changed