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/congatec/common/Makefile b/board/congatec/common/Makefile
index 2db0fc1..f8170d9 100644
--- a/board/congatec/common/Makefile
+++ b/board/congatec/common/Makefile
@@ -7,7 +7,7 @@
 
 MINIMAL=
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 ifndef CONFIG_TPL_BUILD
 ifdef CONFIG_SPL_INIT_MINIMAL
 MINIMAL=y