volser: Use the new IH_CREATE_INIT function

Use IH_CREATE_INIT when restoring volume data, so we don't open each
restored data file twice.

Change-Id: I67b3df1c5777a6b022644b042f405dbd6a1976a0
Reviewed-on: http://gerrit.openafs.org/9970
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>