Convert CONFIG_SYS_LOAD_ADDR to Kconfig

Now that we have consistent usage, migrate this symbol to Kconfig.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Rick Chen <rick@andestech.com>
diff --git a/configs/imx8qm_rom7720_a1_4G_defconfig b/configs/imx8qm_rom7720_a1_4G_defconfig
index 3355635..6287268 100644
--- a/configs/imx8qm_rom7720_a1_4G_defconfig
+++ b/configs/imx8qm_rom7720_a1_4G_defconfig
@@ -14,6 +14,7 @@
 CONFIG_SPL_SERIAL_SUPPORT=y
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL=y
+CONFIG_SYS_LOAD_ADDR=0x80280000
 CONFIG_FIT=y
 CONFIG_SPL_LOAD_FIT=y
 CONFIG_SPL_FIT_GENERATOR="arch/arm/mach-imx/mkimage_fit_atf.sh"