coresight: byte-cntr: Add support for streaming interface for ETR

Add support for a streaming interface for TMC ETR to allow for continuous
log collection to secondary storage. An interrupt based mechanism is used
to stream out the data from the device. The streaming interface cannot be
used in conjunction with the traditional ETR read operation.

Change-Id: Ie80f817740fe3fddbb7fe95b02263525b0bff6e8
Signed-off-by: Mulu He <muluhe@codeaurora.org>