global: Use CONFIG_XPL_BUILD instead of CONFIG_SPL_BUILD

Complete this rename for all directories outside arch/ board/ drivers/
and include/

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/scripts/Kbuild.include b/scripts/Kbuild.include
index 5daceb2..b70b75e 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -324,7 +324,7 @@
 # do not delete intermediate files automatically
 .SECONDARY:
 
-ifdef CONFIG_SPL_BUILD
+ifdef CONFIG_XPL_BUILD
 SPL_ := SPL_
 ifeq ($(CONFIG_VPL_BUILD),y)
 SPL_TPL_ := VPL_