LU-14513 osd: release o_guard before quota acquisition

LU-14513 osd: release o_guard before quota acquisition

to avoid deadlocks as regular transactions (like write) start
a transaction, then grab o_guard.

Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I2678677ed6c213e4bed30cc1218e48b8f2900dc4
Reviewed-on: https://review.whamcloud.com/42018
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Wang Shilong <wshilong@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>