imx8-u-boot: Fix SPL guard option

We should guard the SPL nodes against CONFIG_SPL_BUILD to fix
the following build error when the blobs are absent:

binman: Fail open first container file mx8qm-ahab-container.img

Signed-off-by: Fabio Estevam <festevam@denx.de>
diff --git a/arch/arm/dts/imx8qm-u-boot.dtsi b/arch/arm/dts/imx8qm-u-boot.dtsi
index 442e64b..a3e0af4 100644
--- a/arch/arm/dts/imx8qm-u-boot.dtsi
+++ b/arch/arm/dts/imx8qm-u-boot.dtsi
@@ -10,7 +10,7 @@
 };
 
 &binman {
-#ifdef CONFIG_SPL
+#ifdef CONFIG_SPL_BUILD
 	u-boot-spl-ddr {
 		align = <4>;
 		align-size = <4>;
diff --git a/arch/arm/dts/imx8qxp-u-boot.dtsi b/arch/arm/dts/imx8qxp-u-boot.dtsi
index e8df5bb..7622c40 100644
--- a/arch/arm/dts/imx8qxp-u-boot.dtsi
+++ b/arch/arm/dts/imx8qxp-u-boot.dtsi
@@ -10,7 +10,7 @@
 };
 
 &binman {
-#ifdef CONFIG_SPL
+#ifdef CONFIG_SPL_BUILD
 	u-boot-spl-ddr {
 		align = <4>;
 		align-size = <4>;