[MIPS] Cleanup memory managment initialization.
Historically plat_mem_setup did the entire platform initialization. This was rather impractical because it meant plat_mem_setup had to get away without any kind of memory allocator. To keep old code from breaking plat_setup was just renamed to plat_setup and a second platform initialization hook for anything else was introduced. Signed-off-by: Ralf Baechle <email@example.com>