arm: fix bare-metal memory setup.
arm: fix bare-metal memory setup.

The bare-metal configuration option still configured memory with the old scheme
that no-longer works. This change unifies the code so there aren't any differences.
(transplanted from f33fab6214c4d9c48d8d7e405413410d860cca9b)

LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5,LingxiaoJIA/gem5