[U-Boot] powerpc 4xx support

[Ivan Mikhaylov1]

hi everyone, I saw that powerpc 4xx cpus were removed from powerpc cpu tree with this commit 
98f705c9cefdfdba62c069821bbba10273a0a8ed
powerpc: remove 4xx support

I can help to maintain this tree with further support and needs. As I understood reason of this 
removal was change to Kconfig. Anything else should be done? In this case what process should be?
1. get cpu 4xx before removal
2. do the migration to kconfig
3. send patches via uboot mail list
something like this?