Rename CONFIG_SYS_TEXT_BASE to CONFIG_TEXT_BASE

The current name is inconsistent with SPL which uses CONFIG_SPL_TEXT_BASE
and this makes it imposible to use CONFIG_VAL().

Rename it to resolve this problem.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/imx8mn-u-boot.dtsi b/arch/arm/dts/imx8mn-u-boot.dtsi
index 327d407..95f45ad 100644
--- a/arch/arm/dts/imx8mn-u-boot.dtsi
+++ b/arch/arm/dts/imx8mn-u-boot.dtsi
@@ -152,7 +152,7 @@
 					arch = "arm64";
 					compression = "none";
 					description = "U-Boot (64-bit)";
-					load = <CONFIG_SYS_TEXT_BASE>;
+					load = <CONFIG_TEXT_BASE>;
 					type = "standalone";
 
 					uboot-blob {