regulator: pwm: per instance struct regulator_desc

regulator: pwm: per instance struct regulator_desc

The pwm regulator instances modify struct regulator_desc. To handle more than
1 regulator, we must make ensure each instance has its own struct
regulator_desc to avoid data corruption.

Change-Id: I8a842e57111676b55506b2230949fb1544a1136b
Signed-off-by: Peter De Schrijver <pdeschrijver@nvidia.com>
Reviewed-on: http://git-master/r/1226162
GVS: Gerrit_Virtual_Submit
Reviewed-by: Shreshtha Sahu <ssahu@nvidia.com>
Reviewed-by: Bharat Nihalani <bnihalani@nvidia.com>