Windows: RXAFS_GetVolumeStatus no PRSFS_READ check

Since d2d591caf2c9b4cf2ebae708cc9b4c8b78ca5a5a the file server no
longer performs a PRSFS_READ access check for the GetVolumeStatus RPC.
The cache manager should no longer test for PRSFS_READ as a means of
avoiding RPCs that are known to fail.

Change-Id: I67bd849d337d87657db8e1f0ed2839367b7972a8
Reviewed-on: http://gerrit.openafs.org/10532
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>