regulator: core: set current constraints while setting machine constraints

Machine constraints is configured during regulator register. If current
constraints are provided through machine constraints then it is observed
that sometime the current configured on rail is out of range what machine
constraint has.

Set the current constraints when setting machine constraints to make
sure that rail's current is within the range of given machine constraints.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@linaro.org>