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/comvetia/lxr2/lxr2.c b/board/comvetia/lxr2/lxr2.c
index 1732635..dc7fc20 100644
--- a/board/comvetia/lxr2/lxr2.c
+++ b/board/comvetia/lxr2/lxr2.c
@@ -138,7 +138,7 @@
 	return 0;
 }
 
-#ifdef CONFIG_SPL_BUILD
+#ifdef CONFIG_XPL_BUILD
 #include <spl.h>
 
 #define MX6_PHYFLEX_ERR006282	IMX_GPIO_NR(2, 11)