rk3576: use boot_merger to generate idbloader.img

[amazingfate]

Description

This depends on armbian/rkbin#31.
When idbloader.img is generated by mkimage in u-boot, it can't boot in sd card. To boot in sd card, we have to use close source binary boot_merger from rockchip: https://github.com/rockchip-linux/rkbin/blob/master/tools/boot_merger.
We have to generate RK3576MINIALL.ini with rk3576_boost_v1.02.bin, DDR blob, and u-boot-spl.bin compiled from u-boot source.

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 uboot BOARD=armsom-cm5-io BRANCH=vendor BUILD_MINIMAL=no DEB_COMPRESS=xz
• Tested with armsom-cm5-io, emmc and sd card boot fine.

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