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/kontron_pitx_imx8m.h b/include/configs/kontron_pitx_imx8m.h
index 3dda7b6..3f52d00 100644
--- a/include/configs/kontron_pitx_imx8m.h
+++ b/include/configs/kontron_pitx_imx8m.h
@@ -12,7 +12,7 @@
 	EFI_GUID(0xc898e959, 0x5b1f, 0x4e6d, 0x88, 0xe0, \
 		 0x40, 0xd4, 0x5c, 0xca, 0x13, 0x99)
 
-#ifdef CONFIG_SPL_BUILD
+#ifdef CONFIG_XPL_BUILD
 
 /* malloc f used before GD_FLG_FULL_MALLOC_INIT set */
 #define CFG_MALLOC_F_ADDR		0x182000