Coresight-cti: No need to keep clk being on for cti save/restore

CTI save/restore function only works when CTI have been enabled. In
this situation, clk have been voted. So no need to keep clk being on.

Change-Id: I3a4eb7aec7cc169128f00c2731fecbb68b932ff5
Signed-off-by: Yuanfang Zhang <zhangyuanfang@codeaurora.org>