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/ls1043ardb/Makefile b/board/freescale/ls1043ardb/Makefile
index 5309576..95745bf3a 100644
--- a/board/freescale/ls1043ardb/Makefile
+++ b/board/freescale/ls1043ardb/Makefile
@@ -4,7 +4,7 @@
 
 obj-y += ddr.o
 obj-y += ls1043ardb.o
-ifndef CONFIG_SPL_BUILD
+ifndef CONFIG_XPL_BUILD
 obj-$(CONFIG_NET) += eth.o
 obj-y += cpld.o
 endif