config: Traverse lists when visiting children in all proxy
config: Traverse lists when visiting children in all proxy

This patch makes the all proxy traverse any potential list that is
encountered in the object hierarchy instead of only looking at
children that are SimObjects. An example of where this is useful is
when creating a multi-channel memory system as a list of controllers,
whilst ensuring that the memories are still visible in the system.

andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin,andrewfu0325/gem5-aladdin