UPSTREAM: regulator: pwm: Add support to have multiple instance of pwm regulator

UPSTREAM: regulator: pwm: Add support to have multiple instance of pwm regulator

Some of platforms like Nvidia's Tegra210 Jetson-TX1 platform has
multiple PMW based regulators. Add support to have multiple instances
of the driver by not changing any global data of pwm regulator and
if required, making instance specific copy and then making changes.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from commit f907a0a9498db29fb7c91b798d7af70add7dd86e)

Change-Id: Iafd9b033cd67a76a430024840f70e275a6d22e0d
Signed-off-by: David Wu <david.wu@rock-chips.com>