clk: qcom: gdsc: Add support for ALWAYS_ON gdscs

Some GDSCs might have software control to turn them off, but we might
want to keep them enabled always, in some cases because of lack of
support in kernel to handle a graceful turning off/on of such GDSCs.
Most common instances would be the GDCSs which power up the noc/bus
fabrics, which need bus drivers to handle them and atleast support for
which is missing on all qcom SoCs.

Signed-off-by: Rajendra Nayak <rnayak@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>