dm: regmap: Add a dummy implementation for of-platdata

Add a placeholder for now so that this code will compile. It currently does
nothing.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/core/regmap.c

@@ -15,6 +15,14 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#if CONFIG_IS_ENABLED(OF_PLATDATA)
+int regmap_init_mem_platdata(struct udevice *dev, fdt32_t *reg, int size,
+			     struct regmap **mapp)
+{
+	/* TODO(sjg@chromium.org): Implement this when needed */
+	return 0;
+}
+#else
 int regmap_init_mem(struct udevice *dev, struct regmap **mapp)
 {
 	const void *blob = gd->fdt_blob;
@@ -64,6 +72,7 @@ int regmap_init_mem(struct udevice *dev, struct regmap **mapp)
 
 	return 0;
 }
+#endif
 
 void *regmap_get_range(struct regmap *map, unsigned int range_num)
 {

include/regmap.h

@@ -56,6 +56,9 @@ int regmap_read(struct regmap *map, uint offset, uint *valp);
  */
 int regmap_init_mem(struct udevice *dev, struct regmap **mapp);
 
+int regmap_init_mem_platdata(struct udevice *dev, fdt32_t *reg, int size,
+			     struct regmap **mapp);
+
 /**
  * regmap_get_range() - Obtain the base memory address of a regmap range
  *