ARM: 8423/1: add const qualifier to smp_operations member in structures

The core framework does not modify smp_operations structures.
To clarify it, this commit adds 'const' qualifier to the 'ops'
member of struct of_cpu_method and the 'smp' member of struct
machine_desc.

This change allows each SoC code to add 'const' qualifier to its
smp_operation structure.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>