Currently Palma regulator driver support the ramp delay
through rail specific platform data.

As regulator framework support the configuration of ramp
delay through regulator constraint, using the framework
method and removing the platform specific data approach.
Signed-off-by: NLaxman Dewangan <ldewangan@nvidia.com>
Acked-by: NGraeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>