dump.f2fs: update dump_usage() for directory dumping

Add missing usage for directory dumping functionality of dump.f2fs
as below:

  -r dump out from the root inode
  -f do not prompt before dumping
  -y alias for -f
  -o dump inodes to the given path
  -P preserve mode/owner/group for dumped inode

Cc: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
1 file changed