[MIPS] Fix sparsemem support.

Move memory_present() in arch/mips/kernel/setup.c. When using sparsemem
extreme, this function does an allocate for bootmem. This would always
fail since init_bootmem hasn't been called yet.
    
Move memory_present after free_bootmem. This only marks actual memory
ranges as present instead of the entire address space.
    
Signed-off-by: Chad Reese  <creese@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/mm/init.c

@@ -227,7 +227,7 @@ void __init mem_init(void)
 	for (tmp = 0; tmp < max_low_pfn; tmp++)
 		if (page_is_ram(tmp)) {
 			ram++;
-			if (PageReserved(mem_map+tmp))
+			if (PageReserved(pfn_to_page(tmp)))
 				reservedpages++;
 		}