coresight: conditionally vote for cti clk in probe

To support acknowledging CTI interrupt from atomic context and/or CTI
save and restore in the absence of hardware clock vote, conditionally
vote for CTI clocks during CoreSight CTI driver probe.

Change-Id: I50d7ceb0381bdaca197ab483d5e2a51246d94b1b
Signed-off-by: Aparna Das <adas@codeaurora.org>