LU-12538 lod: Add missed qos_rr_init

LU-12538 lod: Add missed qos_rr_init

The new lmv space hash code uses the lu_qos_rr struct, but
forgot to init it fully.  Specifically, the spin lock isn't
inited, causing failures.

Signed-off-by: Patrick Farrell <pfarrell@whamcloud.com>
Change-Id: Id410a8dc61980b880eab7e151b85c417a8439fd5
Reviewed-on: https://review.whamcloud.com/35490
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Lai Siyao <lai.siyao@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>