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/armv7/start.S b/arch/arm/cpu/armv7/start.S
index 7730a16..b63481b 100644
--- a/arch/arm/cpu/armv7/start.S
+++ b/arch/arm/cpu/armv7/start.S
@@ -279,7 +279,7 @@
 	orr	r2, r4, r2		@ r2 has combined CPU variant + revision
 
 /* Early stack for ERRATA that needs into call C code */
-#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
+#if defined(CONFIG_XPL_BUILD) && defined(CONFIG_SPL_STACK)
 	ldr	r0, =(CONFIG_SPL_STACK)
 #else
 	ldr	r0, =(SYS_INIT_SP_ADDR)