make fileserver avoid salvage loop on init failure

make fileserver avoid salvage loop on init failure

if the vlserver or prserver setup can't succeed, it doesn't indicate
a condition which salvaging is required to fix; instead, come up
and retry in the background.

Reviewed-on: http://gerrit.openafs.org/428
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>