Merge patch series "alist: Implement a pointer list / array of structs"

Simon Glass <sjg@chromium.org> says:

This data structure provides a list of pointers / array of structures.
I was planning to use it for the lmb restructure, to allow it to
support any number of entries, but then I gave up on it.

There are quite a few places in U-Boot where such a list would be
useful, since it supports growing the array.

[...]
Example:

 struct my_struct obj;
 struct my_struct *ptr = alist_add(&lst, &obj, struct my_struct);

 // now ptr is in the list

[trini: Reword the cover letter slightly, do not merge the RFC portion]