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/freescale/p1010rdb/Makefile b/board/freescale/p1010rdb/Makefile
index a00806e..df4e800 100644
--- a/board/freescale/p1010rdb/Makefile
+++ b/board/freescale/p1010rdb/Makefile
@@ -4,7 +4,7 @@
 
 MINIMAL=
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 ifndef CONFIG_TPL_BUILD
 ifdef CONFIG_SPL_INIT_MINIMAL
 MINIMAL=y
@@ -15,7 +15,7 @@
 ifdef MINIMAL
 obj-y	+= spl_minimal.o
 else
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 obj-y	+= spl.o
 endif
 obj-y	+= p1010rdb.o