clk: qcom: Add support for regulator based GDSC control

Support globally distributed switch controller(GDSC) as regulator. This
will enable the clients to use the regulator framework to enable/disable
the GDSCs.

The hw_ctrl/domain_ctrl registers which might be required to be enabled
before the GDSC are modelled using syscon framework.

Change-Id: I2d63105d032ab16d5555722680f4371c831823cd
Signed-off-by: Taniya Das <tdas@codeaurora.org>
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>