Windows: remove faulty assumptions about device names in vol-salvage

Windows: remove faulty assumptions about device names in vol-salvage

The implementation has an assumption that all disk volumes have an
object name of \Device\HarddiskXXX (where XXX is a number).  This is
wrong since the name is purely a convention and since about WXP they
have been called \Device\HarddiskVolumeXXX.

Either way it is spurious to assume the format and then try to compare
the XXX.  This change just compares the strings.  This is done in a
case insenstive manner which is the safer option.  It is quite
feasible, but very unlikely that someone will uses 'case sensitively
different' object names.

Change-Id: Ifa91c88f2b17f747f30541b8833b722cf5993e48
Reviewed-on: http://gerrit.openafs.org/3745
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>