MIPS: SGI-IP27: move registering of smp ops into IP27 specific code

Calling register_smp_ops() in plat_mem_setup() is still early enough.
So by doing this we could remove the ugly #ifdef CONFIG_SGI_IP27 in
fw/arc/init.c.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Paul Burton <paul.burton@mips.com>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org