salvager: fix filesystem path truncation

salvager: fix filesystem path truncation

Fix filesystem path truncation for vice partitions beyond /vicepz.

Commit 3d7388b7 moved the filesystem path to a fixed size buffer,
however the path of the filesystem to be salvaged is truncated for
partitions with two character ids (e.g. /vicepaa), in which case
the salvager will salvager the wrong partition, or abort if the
truncated path is not present.

Change-Id: Iadf45268514ef5045a4481950f213abecbb20b33
Reviewed-on: http://gerrit.openafs.org/5469
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Jeffrey Altman <jaltman@openafs.org>