hsmd: support HSM_VERSION 6

Changelog-Changed: hsmd: the hsmd now supports HSM_VERSION 6

This is actually optional, everything should be ok leaving native hsmd
support at HSM_VERSION 5.

Author: ksedgwic

hsmd/hsmd.c

@@ -436,7 +436,7 @@ static struct io_plan *init_hsm(struct io_conn *conn,
 	struct secret *hsm_encryption_key;
 	struct bip32_key_version bip32_key_version;
 	u32 minversion, maxversion;
-	const u32 our_minversion = 4, our_maxversion = 5;
+	const u32 our_minversion = 4, our_maxversion = 6;
 
 	/* This must be lightningd. */
 	assert(is_lightningd(c));

hsmd/libhsmd.c

@@ -1188,7 +1188,7 @@ static u8 *handle_get_per_commitment_point(struct hsmd_client *c, const u8 *msg_
 		return hsmd_status_bad_request_fmt(
 		    c, msg_in, "bad per_commit_point %" PRIu64, n);
 
-	if (n >= 2) {
+	if (hsmd_mutual_version < 6 && n >= 2) {
 		old_secret = tal(tmpctx, struct secret);
 		if (!per_commit_secret(&shaseed, old_secret, n - 2)) {
 			return hsmd_status_bad_request_fmt(