coresight: Add snapshot of remote etm driver

Add snapshot for coresight remote etm driver from msm-4.19
commit c953c9b6eb1f ("include/linux: add notifier for fps change").
Make necessary change to adopt coresight framework change.

Change-Id: If351486dce567b979e56103385682d9a0e40edbf
Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>