ARM: shmobile: pm: fix init sections

Add the __init section for the functions which are called
at init time.

Signed-off-by: Daniel Lezcano <daniel.linaro.org>
Acked-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>