LU-9733 obd: fix fsname parsing

LU-9733 obd: fix fsname parsing

Lustre support Lustre fsname started with numbers.
So here we should try fsname firstly, if it failed,
fall back to number parsing.

Change-Id: Idd98b9fdc8375729faa61f51251caa101035dd93
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-on: https://review.whamcloud.com/27916
Tested-by: Jenkins
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Gu Zheng <gzheng@ddn.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>