MIPS: init: Fix reservation of memory between PHYS_OFFSET and mem start

Fix calculation of the size for reserving memory between PHYS_OFFSET
and real memory start.

Fixes: a94e4f24 ("MIPS: init: Drop boot_mem_map")
Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

arch/mips/kernel/setup.c

@@ -321,7 +321,7 @@ static void __init bootmem_init(void)
 	 * Reserve any memory between the start of RAM and PHYS_OFFSET
 	 */
 	if (ramstart > PHYS_OFFSET)
-		memblock_reserve(PHYS_OFFSET, PFN_UP(ramstart) - PHYS_OFFSET);
+		memblock_reserve(PHYS_OFFSET, ramstart - PHYS_OFFSET);
 
 	if (PFN_UP(ramstart) > ARCH_PFN_OFFSET) {
 		pr_info("Wasting %lu bytes for tracking %lu unused pages\n",