restapi: fix filter/weight/balance getter

fixes both get and remove policy units per scheduling
policy.

Change-Id: I0a336e9fe3f8fa77d94469d28ecad64234e9b685
Bug-Url: https://bugzilla.redhat.com/1114944
Bug-Url: https://bugzilla.redhat.com/1115071
Signed-off-by: Gilad Chaplik <gchaplik@redhat.com>