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-rockchip/Makefile b/arch/arm/mach-rockchip/Makefile
index 3b13891..76756c3 100644
--- a/arch/arm/mach-rockchip/Makefile
+++ b/arch/arm/mach-rockchip/Makefile
@@ -15,7 +15,7 @@
 
 obj-spl-$(CONFIG_ROCKCHIP_RK3036) += rk3036-board-spl.o
 
-ifeq ($(CONFIG_SPL_BUILD)$(CONFIG_TPL_BUILD),)
+ifeq ($(CONFIG_XPL_BUILD)$(CONFIG_TPL_BUILD),)
 
 # Always include boot_mode.o, as we bypass it (i.e. turn it off)
 # inside of boot_mode.c when CONFIG_ROCKCHIP_BOOT_MODE_REG is 0.  This way,
@@ -51,5 +51,5 @@
 obj-spl-$(CONFIG_TPL_BUILD) =
 
 # Now add SPL/TPL objects back into the main build
-obj-$(CONFIG_SPL_BUILD) += $(obj-spl-y)
+obj-$(CONFIG_XPL_BUILD) += $(obj-spl-y)
 obj-$(CONFIG_TPL_BUILD) += $(obj-tpl-y)