LU-9716 osc: osc_extent_tree_dump0() implementation is suboptimal

LU-9716 osc: osc_extent_tree_dump0() implementation is suboptimal

Avoid looping in osc_extent_tree_dump() if debugging is disabled.
This helps us save some cpu ticks.

Lustre-change: https://review.whamcloud.com/27866
Lustre-commit: 97115ccd159e4503ca16cb7f68ee7479c780f1cf

Change-Id: I492429d8a6de79f67b5923895ffa58b7fe3a100d
Seagate-bug-id: MRP-4469
Signed-off-by: Andrew Perepechko <andrew.perepechko@seagate.com>
Reviewed-by: Alexander Boyko <alexander.boyko@seagate.com>
Reviewed-by: Alexander Zarochentsev <alexander.zarochentsev@seagate.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Minh Diep <minh.diep@intel.com>
Reviewed-on: https://review.whamcloud.com/28235
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Mike Pershin <mike.pershin@intel.com>
Reviewed-by: John L. Hammond <john.hammond@intel.com>