dm: core: Access device flags through functions

At present flags are stored as part of the device. In preparation for
storing them separately, change the access to go through inline functions.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/remoteproc/rproc-uclass.c b/drivers/remoteproc/rproc-uclass.c
index 773b811..c2d6a4e 100644
--- a/drivers/remoteproc/rproc-uclass.c
+++ b/drivers/remoteproc/rproc-uclass.c
@@ -247,7 +247,7 @@
 			    struct dm_rproc_uclass_pdata *uc_pdata,
 			    const void *data)
 {
-	if (dev->flags & DM_FLAG_ACTIVATED)
+	if (dev_get_flags(dev) & DM_FLAG_ACTIVATED)
 		return 0;
 
 	return -EAGAIN;