fdt: Swap the signature for board_fdt_blob_setup()

This returns a devicetree and updates a parameter with an error code.
Swap it, since this fits better with the way U-Boot normally works. It
also (more easily) allows leaving the existing pointer unchanged.

No yaks were harmed in this change, but there is a very small code-size
reduction.

For sifive, the OF_BOARD option must be set for the function to be
called, so there is no point in checking it again. Also OF_SEPARATE is
defined always.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>
[trini: Update total_compute]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/board/broadcom/bcmstb/bcmstb.c b/board/broadcom/bcmstb/bcmstb.c
index bc05aec..e655f61 100644
--- a/board/broadcom/bcmstb/bcmstb.c
+++ b/board/broadcom/bcmstb/bcmstb.c
@@ -130,9 +130,10 @@
 	return 0;
 }
 
-void *board_fdt_blob_setup(int *err)
+int board_fdt_blob_setup(void **fdtp)
 {
-	*err = 0;
 	/* Stored the DTB address there during our init */
-	return (void *)prior_stage_fdt_address;
+	*fdtp = (void *)prior_stage_fdt_address;
+
+	return 0;
 }