bucoord: restore requires server and partition

bucoord: restore requires server and partition

The VolRestoreCmd sub command requires that the user specifies
the server and partition - calls which don't do so won't get past
libcmd. Don't check again in the handler that they have been supplied,
as it confuses things.

Caught by coverity (#985953)

Change-Id: Id4548c117b677bd2048744ade8fd91bb15e0e35e
Reviewed-on: http://gerrit.openafs.org/9547
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>