arch: 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/arch/arm/mach-keystone/Makefile b/arch/arm/mach-keystone/Makefile
index 6c7c250..c864317 100644
--- a/arch/arm/mach-keystone/Makefile
+++ b/arch/arm/mach-keystone/Makefile
@@ -10,7 +10,7 @@
 obj-y	+= clock.o
 obj-y	+= mon.o
 CFLAGS_REMOVE_mon.o := $(LTO_CFLAGS)
-ifndef CONFIG_SPL_BUILD
+ifndef CONFIG_XPL_BUILD
 obj-y	+= cmd_clock.o
 obj-y	+= cmd_mon.o
 obj-y	+= cmd_poweroff.o