rockchip: lion-rk3368: Migrate to use common FIT generator

The RK3368 lion board ATF can use bl31.elf like RK3399 and get the FIT
source with generic FIT generator script at:
arch/arm/mach-rockchip/make_fit_atf.py

And then we can use 'BL31' environment to get the path of bl31.elf
instead of copy it into U-Boot folder.

CC: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Signed-off-by: NKever Yang <kever.yang@rock-chips.com>

board/theobroma-systems/lion_rk3368/fit_spl_atf.its

-/* SPDX-License-Identifier: GPL-2.0+ OR X11 */
-/*
- * Copyright (C) 2017 Theobroma Systems Design und Consulting GmbH
- *
- * Minimal dts for a SPL FIT image payload.
- */
-
-/dts-v1/;
-
-/ {
-	description = "FIT image with U-Boot proper, ATF bl31, DTB";
-	#address-cells = <1>;
-
-	images {
-		uboot {
-			description = "U-Boot (64-bit)";
-			data = /incbin/("../../../u-boot-nodtb.bin");
-			type = "standalone";
-			os = "U-Boot";
-			arch = "arm64";
-			compression = "none";
-			load = <0x00200000>;
-		};
-		atf {
-			description = "ARM Trusted Firmware";
-			data = /incbin/("../../../bl31-rk3368.bin");
-			type = "firmware";
-			os = "arm-trusted-firmware";
-			arch = "arm64";
-			compression = "none";
-			load = <0x00100000>;
-			entry = <0x00100000>;
-		};
-
-		fdt {
-			description = "RK3368-uQ7 (Lion) flat device-tree";
-			data = /incbin/("../../../u-boot.dtb");
-			type = "flat_dt";
-			compression = "none";
-		};
-	};
-
-	configurations {
-		default = "conf";
-		conf {
-			description = "Theobroma Systems RK3368-uQ7 (Puma) SoM";
-			firmware = "atf";
-			loadables = "uboot";
-			fdt = "fdt";
-		};
-	};
-};

configs/lion-rk3368_defconfig

@@ -20,7 +20,6 @@ CONFIG_ANDROID_BOOT_IMAGE=y
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y
 CONFIG_SPL_LOAD_FIT=y
-CONFIG_SPL_FIT_SOURCE="board/theobroma-systems/lion_rk3368/fit_spl_atf.its"
 CONFIG_BOOTSTAGE=y
 CONFIG_SPL_BOOTSTAGE=y
 CONFIG_BOOTSTAGE_REPORT=y