MIPS: Fix info about plat_setup in arch_mem_init comment

Signed-off-by: NRafał Miłecki <zajec5@gmail.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/7607/Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/setup.c

@@ -485,7 +485,7 @@ static void __init bootmem_init(void)
  * NOTE: 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
+ * breaking plat_setup was just renamed to plat_mem_setup and a second platform
  * initialization hook for anything else was introduced.
  */