video: sm501.c: add weak default functions

For boards using sm501/sm502 on PCI bus some driver
functions normaly defined in the board code are not
needed and empty. Provide weak default functions for
them and do not enforce board code to define empty
functions.

Signed-off-by: Anatolij Gustschin <agust@denx.de>

drivers/video/sm501.c

@@ -95,6 +95,34 @@ static struct pci_device_id sm501_pci_tbl[] = {
 };
 #endif
 
+/*
+ * We do not enforce board code to provide empty/unused
+ * functions for this driver and define weak default
+ * functions here.
+ */
+unsigned int __board_video_init (void)
+{
+	return 0;
+}
+
+unsigned int board_video_init (void)
+			__attribute__((weak, alias("__board_video_init")));
+
+unsigned int __board_video_get_fb (void)
+{
+	return 0;
+}
+
+unsigned int board_video_get_fb (void)
+			__attribute__((weak, alias("__board_video_get_fb")));
+
+void __board_validate_screen (unsigned int base)
+{
+}
+
+void board_validate_screen (unsigned int base)
+			__attribute__((weak, alias("__board_validate_screen")));
+
 /*-----------------------------------------------------------------------------
  * video_hw_init --
  *-----------------------------------------------------------------------------