vol: fdHandleAllocateChunk should init all fields

vol: fdHandleAllocateChunk should init all fields

fdHandleAllocateChunk() failed to initialize the fd_ihnext
and fd_ihprev fields.

Reviewed-on: http://gerrit.openafs.org/3671
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit bae39a9aa3738878708f4c67d17750beca4d6dca)

Change-Id: I9fa401cb4ddec886a3f39ddfb926ce0be8cfa96e
Reviewed-on: http://gerrit.openafs.org/3832
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>