soc: qcom: Handle bus scaling only if enabled

Handle cases when bus scaling is not enabled. PIL driver today assumes
bus scaling support and if not enabled fails to bring the subsystem out
of reset. Use stub when bus scaling is not enabled instead of failing.
Similarly proxy unvote case keeps printing the warning flooding the
console when bus scaling is stubbed out. Add checks to make sure we
print the warnings and call into bus APIs only when bus scaling is
enabled.

Change-Id: I0c627660bd379f6f733dc9cdb868164944701864
Signed-off-by: Channagoud Kadabi <ckadabi@codeaurora.org>