clk: qcom: gdsc-regulator: Add support for proxy consumers

Add support to enforce proxy consumer requests defined in device
tree for gdsc-regulator devices. These can be used to
ensure that regulators are not accidentally disabled or
scaled down before all consumers have had a chance to
make their own requests.

Change-Id: I495283866fb61fb54e5ecf6ed3789abaa4ae66d1
Signed-off-by: Vivek Aknurwar <viveka@codeaurora.org>