[FAB-5937] Bad default mod_policy for Consortiums

The mod_policy for /Channel/Consortiums/Admins currently defaults to
Admins (itself), but this should be /Channel/Orderer/Admins.

This CR fixes configtxgen to set the appropriate default.

Change-Id: Icbcea833fb6bb7f6c8528edacb575f9f2b3be6ee
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

common/tools/configtxgen/provisional/provisional.go

@@ -194,6 +194,7 @@ func New(conf *genesisconfig.Profile) Generator {
 				Type:  int32(cb.Policy_SIGNATURE),
 				Value: utils.MarshalOrPanic(cauthdsl.AcceptAllPolicy),
 			},
+			ModPolicy: OrdererAdminsPolicy,
 		}
 
 		bs.consortiumsGroups = append(bs.consortiumsGroups, tcg)