coresight: tgu: Add support for Trigger Generation Unit

This driver provides support for Trigger Generation Unit that is
used to detect patterns or sequences on a given set of signals.
TGU is used to monitor a particular bus within a given region to
detect illegal transaction sequences or slave responses. It is also
used to monitor a data stream to detect protocol violations and to
provide a trigger point for centering data around a specific event
within the trace data buffer.

Change-Id: I850bdff94493bbb981b5d17afc766804fe70fd64
Signed-off-by: Rama Aparna Mallavarapu <aparnam@codeaurora.org>