dm: i2c: Add a dm_ prefix to driver model bus speed functions

As with i2c_read() and i2c_write(), add a dm_ prefix to the driver model
versions of these functions to avoid conflicts.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
index eafa457..a6991bf 100644
--- a/drivers/i2c/i2c-uclass.c
+++ b/drivers/i2c/i2c-uclass.c
@@ -325,7 +325,7 @@
 	return ret;
 }
 
-int i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
+int dm_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct dm_i2c_bus *i2c = bus->uclass_priv;
@@ -346,12 +346,7 @@
 	return 0;
 }
 
-/*
- * i2c_get_bus_speed:
- *
- *  Returns speed of selected I2C bus in Hz
- */
-int i2c_get_bus_speed(struct udevice *bus)
+int dm_i2c_get_bus_speed(struct udevice *bus)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);
 	struct dm_i2c_bus *i2c = bus->uclass_priv;
@@ -440,7 +435,7 @@
 	i2c->speed_hz = fdtdec_get_int(gd->fdt_blob, dev->of_offset,
 				     "clock-frequency", 100000);
 
-	return i2c_set_bus_speed(dev, i2c->speed_hz);
+	return dm_i2c_set_bus_speed(dev, i2c->speed_hz);
 }
 
 static int i2c_post_bind(struct udevice *dev)