clk: qcom: clk-cpu-osm: Vote on the L3 cluster clocks enable

Due to the way the voter clock framework is structured, the
rate requests for the L3 cluster clocks would not make it to
the parent l3_clk unless they are enabled. Place a proxy vote
on the cluster clocks so that the client drivers who only care
about scaling them needn't enable them explicitly.

Change-Id: I0b4a9871c0506695241077de1d4da62b6178acbc
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>