i2c: Update for new sequence numbers

Use the new sequence number in all cases. Drop the logic to check for a
valid number in designware_i2c, since it will always be valid.

Also drop the numbering in the uclass, since we can rely on driver
model giving us the right sequence numbers.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c
index 1fcb8c6..a4d59b6 100644
--- a/drivers/i2c/mvtwsi.c
+++ b/drivers/i2c/mvtwsi.c
@@ -823,9 +823,9 @@
 	struct mvtwsi_registers *twsi = dev_read_addr_ptr(bus);
 
 	/* Disable the hidden slave in i2c0 of these platforms */
-	if ((IS_ENABLED(CONFIG_ARMADA_38X) || IS_ENABLED(CONFIG_ARCH_KIRKWOOD)
-				|| IS_ENABLED(CONFIG_ARMADA_8K))
-			&& bus->req_seq == 0)
+	if ((IS_ENABLED(CONFIG_ARMADA_38X) ||
+	     IS_ENABLED(CONFIG_ARCH_KIRKWOOD) ||
+	     IS_ENABLED(CONFIG_ARMADA_8K)) && !dev_seq(bus))
 		twsi_disable_i2c_slave(twsi);
 
 	return 0;