UPSTREAM: regulator: core: Add support for active-discharge configuration

UPSTREAM: regulator: core: Add support for active-discharge configuration

Add support to enable/disable active discharge of regulator via
machine constraints. This configuration is done when setting
machine constraint during regulator register and if regulator
driver implemented the callback ops.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from commit 909f7ee0b5f30f735e16864a7ed18d2e6123e6d9)

Change-Id: I9b989b8b88e9d8e765a6cefb1a189c86e7c87dbe
Signed-off-by: David Wu <david.wu@rock-chips.com>