dm: Protect device_unbind() with CONFIG_DM_DEVICE_REMOVE

Since device_unbind() is also defined in device-remove.c,
which is compiled in only in case CONFIG_DM_DEVICE_REMOVE
is defined, protect the device_unbind() prototype with the
same CONFIG_DM_DEVICE_REMOVE check.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Cc: Stefan Roese <sr@denx.de>
Cc: Tom Rini <trini@ti.com>
Acked-by: Simon Glass <sjg@chromium.org>

include/dm/device-internal.h

@@ -101,7 +101,11 @@ static inline int device_remove(struct udevice *dev) { return 0; }
  * @dev: Pointer to device to unbind
  * @return 0 if OK, -ve on error
  */
+#ifdef CONFIG_DM_DEVICE_REMOVE
 int device_unbind(struct udevice *dev);
+#else
+static inline int device_unbind(struct udevice *dev) { return 0; }
+#endif
 
 #ifdef CONFIG_DM_DEVICE_REMOVE
 void device_free(struct udevice *dev);