km/powerpc: fix ft_board_setup prototype for km82xx & km83xx

Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
diff --git a/board/keymile/km83xx/km83xx.c b/board/keymile/km83xx/km83xx.c
index 1164c2e..154f974 100644
--- a/board/keymile/km83xx/km83xx.c
+++ b/board/keymile/km83xx/km83xx.c
@@ -361,7 +361,7 @@
 	return 0;
 }
 
-void ft_board_setup(void *blob, bd_t *bd)
+int ft_board_setup(void *blob, bd_t *bd)
 {
 	ft_cpu_setup(blob, bd);