The value of tmnxBsxTransPrefPolicySubsCount indicates the
total number of subscribers within this transit prefix policy.
The value of tmnxBsxTransPrefPolicySubsCount is the number of
rows in the table tmnxBsxTransPrefSubTable with matching
tmnxBsxAaGrpPartIndex and tmnxBsxTransPrefPolicyId indices.