ARM: SoC: convert MSM to SMP operations

Convert MSM SMP platforms to use struct smp_operations to provide
their SMP and CPU hotplug operations.

[antypas@xda: Adapt to 8974/hammerhead]

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Cc: David Brown <davidb@codeaurora.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>