regulator: rpm-smd-regulator: move regulator init to arch_initcall

RPM regulator initialization is done at module_init level which is
late in the boot-up sequence and drivers dependent on regulators
do probe deferral.
Move RPM regulator initialization to arch_init level to minimize
probe deferrals by dependent drivers.

Change-Id: I3e0bc7cb46a90eb62418122869c70345da9217ee
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>