all platforms: make show_boot_progress() work again

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/include/common.h b/include/common.h
index 6284b8a..7ba6187 100644
--- a/include/common.h
+++ b/include/common.h
@@ -688,7 +688,7 @@
 /*
  * Board-specific Platform code can reimplement show_boot_progress () if needed
  */
-void __attribute__((weak)) show_boot_progress (int val);
+void show_boot_progress(int val);
 
 #ifdef CONFIG_INIT_CRITICAL
 #error CONFIG_INIT_CRITICAL is deprecated!