regulator: Move regulator drivers to subsys_initcall()

Regulators need to be available early in init in order to allow them
to be available for consumers when requested. This is generally done
by registering them at subsys_initcall() time but not all regulator
drivers have done that. Convert these drivers to do so in order to
mimimise future support.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Mike Rapoport <mike@compulab.co.il>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>