LU-17690 quota: uninitialized var in qmt_lgd_extend_cb()

LU-17690 quota: uninitialized var in qmt_lgd_extend_cb()

fix false warning

Test-Parameters: trivial
Signed-off-by: Alex Zhuravlev <bzzz@whamcloud.com>
Change-Id: I30e530119edd34c2a73487af4cbcc7ee9da46725
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54610
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Arshad Hussain <arshad.hussain@aeoncomputing.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>