clk: add bus voting ops for debug purposes

Add bandwidth voting for clk_summary, clk_show and clk_print_regs
to allow access to the config space of certain multimedia clock
controllers including display, camera, and video.

Change-Id: Ia7b8820cd3fc972caf87530a3105b6c90f37e7c5
Signed-off-by: David Dai <daidavid1@codeaurora.org>