Coresight: add support for device names

Add support to read device names from device tree entries.
This allows using same names for CoreSight devices across different
targets.

Change-Id: Ide3da74533051db38e9a6c5904a7cab42b3be6c1
Signed-off-by: Shashank Mittal <mittals@codeaurora.org>
Signed-off-by: Rama Aparna Mallavarapu <aparnam@codeaurora.org>