coresight: add CTI driver support in upstream implementation

Add CTI driver in upstream implementation of Coresight driver.

This change copies drivers/coresight/coresight-cti.c (commit :
c1551685) to driver/hwtracing/coresight
directory.

Change-Id: I4b4b23755c36254d94bd6698b46f15da19c30712
Signed-off-by: Shashank Mittal <mittals@codeaurora.org>