ARM: dts: imx: Introduce SPL and FIT labels to i.MX8M DTs binman nodes

Add binman_imx_spl and binman_imx_fit labels to nxp-imx8mimage {} and fit {}
nodes respectively, so they can be referened in board DTs no matter how deep
in the top level binman image description they are. Update current board DTs
to use those labels.

Reviewed-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Marek Vasut <marex@denx.de>
diff --git a/arch/arm/dts/imx8mm-verdin-wifi-dev-u-boot.dtsi b/arch/arm/dts/imx8mm-verdin-wifi-dev-u-boot.dtsi
index 90183af..183de46 100644
--- a/arch/arm/dts/imx8mm-verdin-wifi-dev-u-boot.dtsi
+++ b/arch/arm/dts/imx8mm-verdin-wifi-dev-u-boot.dtsi
@@ -35,12 +35,8 @@
 	bootph-pre-ram;
 };
 
-&binman {
-	section {
-		fit {
-			offset = <0x5fc00>;
-		};
-	};
+&binman_imx_fit {
+	offset = <0x5fc00>;
 };
 
 &gpio1 {