DAFS: VnLock after VnWaitQuiescent in VAllocVnode

DAFS: VnLock after VnWaitQuiescent in VAllocVnode

In VAllocVnode, we write-lock the newly-allocated vnode. In DAFS,
however, we need to VnWaitQuiescent_r before VnLock'ing, since VnLock
in DAFS just sets the writer tid/pid. So, in VAllocVnode, move the
VnLock call to after we wait for quiescence, so we don't stomp over
the vnode when someone else has it write-locked.

Change-Id: Ib234634dba9d09eea877bc91660ea3a8a4e2b746
Reviewed-on: http://gerrit.openafs.org/4059
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>