dm: Add support for RAM drivers

Add support for a driver which sets up DRAM and can return information about
the amount of RAM available. This is a first step towards moving RAM init
to driver model.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index cba7c0a..93a3857 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -28,6 +28,7 @@
 	UCLASS_CPU,		/* CPU, typically part of an SoC */
 	UCLASS_CROS_EC,		/* Chrome OS EC */
 	UCLASS_DISPLAY_PORT,	/* Display port video */
+	UCLASS_RAM,		/* RAM controller */
 	UCLASS_ETH,		/* Ethernet device */
 	UCLASS_GPIO,		/* Bank of general-purpose I/O pins */
 	UCLASS_I2C,		/* I2C bus */