srm: Fix regression in srmGetSpaceMetaData

The spec is not precise about what file requests level statuses should
be considered a non-success return code for the srmGetSpaceMetaData
operation itself. It seems however logical to not consider
space-lifetime-expired and exceeded-allocation as failures of the
getSpaceMetaData operation.

Atlas transfers currently fail at NDGF due to this problem.

Target: trunk
Require-notes: no
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6218/