[v4 0/7] Fix Rockchip RK3399 bootstd migration

Hey all,

I took a look at Simon's v3 series to fix the rk3399 bootstd migration, and it changed too much for everything else. I took about half of that series and then reworked a few things. Now only rk3399 platforms change at all and aside from bootcmd changes, the only thing is they now disable true/test/sysboot/showvar/false/exit commands as those were being pulled in from distro and now we don't set that flag. I think the way I changed how we enable BOOTSTD_DEFAULTS should make it easier to perform more SoC migrations.