vos: convertROtoRW misc error reporting problems

vos: convertROtoRW misc error reporting problems

Fixes a few inconsistencies and bugs in some error messages.

Reviewed-on: http://gerrit.openafs.org/7387
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit e1c6ad7d580041caf35f698c9b2241fb45f02361)

Change-Id: Icee86e1750920d50b94e29acc5504bd1a2ea9e6e
Reviewed-on: http://gerrit.openafs.org/7496
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>