qcom: clock: Use clock lists instead of clock arrays

Add a list node field to the generic clock struct. This simplifies the
code in clock-debug.c and clock.c, and also provides a list field that
can be used in the future for maintaining the orphan list.

Change-Id: I5422c3ff129e31a043f2607c78d04da6e5b276ed
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>