include: 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/include/configs/librem5.h b/include/configs/librem5.h
index 876b02f..571c772 100644
--- a/include/configs/librem5.h
+++ b/include/configs/librem5.h
@@ -41,7 +41,7 @@
 #define CONSOLE		"ttymxc0"
 #endif
 
-#ifndef CONFIG_SPL_BUILD
+#ifndef CONFIG_XPL_BUILD
 #define BOOT_TARGET_DEVICES(func) \
 	func(MMC, mmc, 0) \
 	func(USB, usb, 0) \