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/arm11/Makefile b/arch/arm/cpu/arm11/Makefile
index 5dfa01a..38a3e4d 100644
--- a/arch/arm/cpu/arm11/Makefile
+++ b/arch/arm/cpu/arm11/Makefile
@@ -5,6 +5,6 @@
 
 obj-y	= cpu.o
 
-ifneq ($(CONFIG_SPL_BUILD),y)
+ifneq ($(CONFIG_XPL_BUILD),y)
 obj-$(CONFIG_EFI_LOADER) += sctlr.o
 endif