kvdb: move channeldb/kvdb to top level

channeldb/migration20/migration.go

@@ -5,7 +5,7 @@ import (
 	"fmt"
 
 	"github.com/btcsuite/btcd/wire"
-	"github.com/lightningnetwork/lnd/channeldb/kvdb"
+	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/tlv"
 )
 

channeldb/migration20/migration_test.go

@@ -3,8 +3,8 @@ package migration20
 import (
 	"testing"
 
-	"github.com/lightningnetwork/lnd/channeldb/kvdb"
 	"github.com/lightningnetwork/lnd/channeldb/migtest"
+	"github.com/lightningnetwork/lnd/kvdb"
 )
 
 var (