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-socfpga/include/mach/boot0.h b/arch/arm/mach-socfpga/include/mach/boot0.h
index c78def5..2676d6c 100644
--- a/arch/arm/mach-socfpga/include/mach/boot0.h
+++ b/arch/arm/mach-socfpga/include/mach/boot0.h
@@ -9,7 +9,7 @@
 _start:
 	ARM_VECTORS
 
-#ifdef CONFIG_SPL_BUILD
+#ifdef CONFIG_XPL_BUILD
 	.balignl 64,0xf33db33f;
 
 	.word	0x1337c0d3;	/* SoCFPGA preloader validation word */