Let rk35xx and rockchip-rk3588 family use same boot script for legacy/vendor branch

[amazingfate]

Description

Family rk35xx legacy/vendor branch use boot-rockchip64.cmd which is the same as mainline current/edge branch, while rockchip-rk3588 legacy/vendor branch use boot-rk3588-legacy.cmd.
boot-rk3588-legacy.cmd was copied from boot-rockchip64.cmd and added supported for overlay: #4734, and rk35xx legacy/vendor are using the same kernel as rockchip-rk3588 legacy/vendor, so we can let the two family use the same boot script.

Since that copy, there are some fixes on boot-rockchip64.cmd like #6027, so I just synced boot-rockchip64.cmd to boot-rk3588-legacy.cmd, and then rename it to boot-rk35xx.cmd.

Now diff config/bootscripts/boot-rockchip64.cmd config/bootscripts/boot-rk35xx.cmd has the following output:

$ diff config/bootscripts/boot-rockchip64.cmd config/bootscripts/boot-rk35xx.cmd 
53a54,56
> 	elif load ${devtype} ${devnum}:${distro_bootpart} ${load_addr} ${prefix}dtb/rockchip/overlay/${overlay_file}.dtbo; then
> 		echo "Applying kernel provided DT overlay ${overlay_file}.dtbo"
> 		fdt apply ${load_addr} || setenv overlay_error "true"

So boot-rk35xx.cmd is the copy of boot-rockchip64.cmd adding overlay file with no prefix support.

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Please also note any relevant details for your test configuration.

• ./compile.sh BOARD=armsom-sige3 BRANCH=vendor BUILD_MINIMAL=no DEB_COMPRESS=xz KERNEL_CONFIGURE=no RELEASE=noble KERNEL_GIT=shallow BUILD_DESKTOP=yes DESKTOP_APPGROUPS_SELECTED= DESKTOP_ENVIRONMENT=gnome DESKTOP_ENVIRONMENT_CONFIG_NAME=config_base

Checklist:

Please delete options that are not relevant.

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• Any dependent changes have been merged and published in downstream modules