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/cpu/arm926ejs/Makefile b/arch/arm/cpu/arm926ejs/Makefile
index 8cfe3f0..7551388 100644
--- a/arch/arm/cpu/arm926ejs/Makefile
+++ b/arch/arm/cpu/arm926ejs/Makefile
@@ -6,7 +6,7 @@
 extra-y	= start.o
 obj-y	= cpu.o cache.o
 
-ifdef	CONFIG_SPL_BUILD
+ifdef	CONFIG_XPL_BUILD
 ifdef	CONFIG_SPL_NO_CPU_SUPPORT
 extra-y	:=
 endif