ARM: SoC: convert spear13xx to SMP operations

Convert the spear13xx platform to use struct smp_operations to provide
its SMP and CPU hotplug operations.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Shiraz Hashim <shiraz.hashim@st.com>
Cc: spear-devel@list.st.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>