LU-17669 test: using unintialized variable in sanity:160n

LU-17669 test: using unintialized variable in sanity:160n

This patch fix a simple typo of unintialized variable.

Fixes: d813c75df ("LU-14688 mdt: changelog purge deletes plain llog")

Test-Parameters: trivial testlist=sanity env=ONLY=160n
Change-Id: I2e29cce33733c925dfe9a53c06af7ac17b2c6be3
Signed-off-by: Li Xi <lixi@ddn.com>
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/54549
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alexander Boyko <alexander.boyko@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>