dm: i2c: Add a function to find out the chip offset length

We can currently set this but there is no API function to get it. Add one.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>
Acked-by: Heiko Schocher<hs@denx.de>
diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c
index b8eb2d6..eaba965 100644
--- a/drivers/i2c/i2c-uclass.c
+++ b/drivers/i2c/i2c-uclass.c
@@ -415,6 +415,13 @@
 	return 0;
 }
 
+int i2c_get_chip_offset_len(struct udevice *dev)
+{
+	struct dm_i2c_chip *chip = dev_get_parent_platdata(dev);
+
+	return chip->offset_len;
+}
+
 int i2c_deblock(struct udevice *bus)
 {
 	struct dm_i2c_ops *ops = i2c_get_ops(bus);