clk: Add a unique string for clock driver's kernel log messages

Certain clock warnings are hard to notice and easy to ignore.
As a result, issues with the clock driver have gone unnoticed
and have caused hard-to-debug issues in other drivers. Add a
'clk:' prefix to all the relevant clock driver logs for scripts
to automatically be able to catch these issues.

Change-Id: Ic1acec964114c4a3b07f9c19a3e0e6f98af0f091
Signed-off-by: Deepak Katragadda <dkatraga@codeaurora.org>