tegra: Add a board ID function

Add a way of displaying a numeric board ID on start-up.

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/board/nvidia/common/board.c b/board/nvidia/common/board.c
index f1a9496..b5a69df 100644
--- a/board/nvidia/common/board.c
+++ b/board/nvidia/common/board.c
@@ -81,10 +81,20 @@
 #endif
 }
 
+__weak int tegra_board_id(void)
+{
+	return -1;
+}
+
 #ifdef CONFIG_DISPLAY_BOARDINFO
 int checkboard(void)
 {
-	printf("Board: %s\n", CONFIG_TEGRA_BOARD_STRING);
+	int board_id = tegra_board_id();
+
+	printf("Board: %s", CONFIG_TEGRA_BOARD_STRING);
+	if (board_id != -1)
+		printf(", ID: %d\n", board_id);
+	printf("\n");
 
 	return 0;
 }