MIPS: Malta: Allow use of MIPS CPS SMP implementation

This patch simply attempts to register the MIPS Coherent Processing
System SMP implementation when it is enabled. If registering that fails
for some reason (like the Kconfig option being disabled or a lack of
hardware support) then we fall back to the same SMP implementations as
before.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6365/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>