scripts: Switch to more portable python3

Signed-off-by: Jensen Huang <jensenhuang@friendlyarm.com>

kernel-5.10/scripts/bmpconvert

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0 */
 # -*- coding: utf-8 -*-
 

u-boot/arch/arm/mach-rockchip/decode_bl31.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 #
 # Copyright (C) 2020 Rockchip Electronics Co., Ltd
 #

u-boot/arch/arm/mach-rockchip/make_fit_atf.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2
+#!/usr/bin/env python3
 """
 A script to generate FIT image source for rockchip boards
 with ARM Trusted Firmware

u-boot/make.sh

@@ -725,8 +725,8 @@ function pack_fit_image()
 		echo "ERROR: No 'dtc', please: apt-get install device-tree-compiler"
 		exit 1
 	elif [ "${ARM64_TRUSTZONE}" == "y" ]; then
-		if ! which python2 >/dev/null 2>&1 ; then
+		if ! which python3 >/dev/null 2>&1 ; then
-			echo "ERROR: No python2"
+			echo "ERROR: No python3"
 			exit 1
 		fi
 	fi
@@ -792,7 +792,7 @@ select_ini_file
 handle_args_late
 sub_commands
 clean_files
-make PYTHON=python2 CROSS_COMPILE=${TOOLCHAIN} all --jobs=${JOB}
+make PYTHON=python3 CROSS_COMPILE=${TOOLCHAIN} all --jobs=${JOB}
 pack_images
 finish
 echo ${TOOLCHAIN}