board: Use CONFIG_XPL_BUILD instead of CONFIG_SPL_BUILD

Use the new symbol to refer to any 'SPL' build, including TPL and VPL

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/grinn/liteboard/board.c b/board/grinn/liteboard/board.c
index 07bb5b7..c2a44b4 100644
--- a/board/grinn/liteboard/board.c
+++ b/board/grinn/liteboard/board.c
@@ -229,7 +229,7 @@
 	return 0;
 }
 
-#ifdef CONFIG_SPL_BUILD
+#ifdef CONFIG_XPL_BUILD
 void board_boot_order(u32 *spl_boot_list)
 {
 	struct src *psrc = (struct src *)SRC_BASE_ADDR;