MIPS: SGI-IP27: use cpu physid already present while scanning for CPUs

By using cpu physid already present when scanning for CPUs
get_cpu_slice() is unsued and can be removed together with two
other then used functions.

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