LU-11776 utils: add support lfs find with mdt hash flag

LU-11776 utils: add support lfs find with mdt hash flag

The lfs find can use mdt hash flag as a condition. Also
change it can find with one more mdt hash type.

Signed-off-by: Yang Sheng <ys@whamcloud.com>
Change-Id: I599bb1a3cc2c9ea2a523f50f119bd93a5520d213
Reviewed-on: https://review.whamcloud.com/39340
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>