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/phytec/pcl063/Makefile b/board/phytec/pcl063/Makefile
index 53c73c9..0f17eb4 100644
--- a/board/phytec/pcl063/Makefile
+++ b/board/phytec/pcl063/Makefile
@@ -4,4 +4,4 @@
 #
 
 obj-y  := pcl063.o
-obj-$(CONFIG_SPL_BUILD) += spl.o
+obj-$(CONFIG_XPL_BUILD) += spl.o