MIPS: SGI-IP27: Store cpu speed when scanning for CPUs and use it later

Remember CPU speed while scanning for available CPUs to avoid
looking it up a second time when printing CPU speed.

Signed-off-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
Signed-off-by: Paul Burton <paulburton@kernel.org>
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