Fix incorrect "successfully mounted" messages

[daneos]

If autosave is not configured to manage NFS mounts or mounts are not supported on current OS, it will still happily report that the mount was successful.

drop-2407391 > save_restoreSet_NFSHost a b c 
Autosave is not configured to manage the file-system mount point.
save_restore:mountFileSystem:successfully mounted 'c'

This fixes this behaviour to show that the mount was not succesful.

drop-2412294 > save_restoreSet_NFSHost a b c
Autosave is not configured to manage the file-system mount point.
save_restore: Can't mount 'c'