dm: Avoid accessing seq directly

At present various drivers etc. access the device's 'seq' member directly.
This makes it harder to change the meaning of that member. Change access
to go through a function instead.

The drivers/i2c/lpc32xx_i2c.c file is left unchanged for now.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/i2c/octeon_i2c.c b/drivers/i2c/octeon_i2c.c
index b1a9cce..100c751 100644
--- a/drivers/i2c/octeon_i2c.c
+++ b/drivers/i2c/octeon_i2c.c
@@ -811,7 +811,7 @@
 	if (ret)
 		return ret;
 
-	debug("TWSI bus %d at %p\n", dev->seq, twsi->base);
+	debug("TWSI bus %d at %p\n", dev_seq(dev), twsi->base);
 
 	/* Start with standard speed, real speed set via DT or cmd */
 	return twsi_init(twsi->base, i2c_slave_addr);