LU-10011 utils: refactor lfs quota codes

LU-10011 utils: refactor lfs quota codes

'lfs quota' default output logic is a bit hard to
understand, refactor codes to make it eaiser to
read.

Lustre-change: https://review.whamcloud.com/29165
Lustre-commit: 49fd1d15daf6a0ccb08dc0269f36530019994be1

Signed-off-by: Wang Shilong <wshilong@ddn.com>
Change-Id: I9b2a5867ed0416ccb92856538ef029bc59ac2c4b
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Reviewed-by: Emoly Liu <emoly.liu@intel.com>
Signed-off-by: Minh Diep <minh.diep@intel.com>
Reviewed-on: https://review.whamcloud.com/30272
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>