dm: core: Don't inline dev_read...() calls with of-platdata

At present if these calls are used with of-platdata, a confusing error is
produced, referring to a function not actually called by the code causing
the problem.

Fix this by not inlining, so that the error mentions the dev_read_...()
function and it is more obvious what is going on.

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

include/dm/read.h

@@ -30,8 +30,7 @@ static inline const struct device_node *dev_np(const struct udevice *dev)
 }
 #endif
 
-#ifndef CONFIG_DM_DEV_READ_INLINE
-
+#if !defined(CONFIG_DM_DEV_READ_INLINE) || CONFIG_IS_ENABLED(OF_PLATDATA)
 /**
  * dev_read_u32() - read a 32-bit integer from a device's DT property
  *