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: I9a78107273f295ecb219f89ec728aa7b9eea27e0
Signed-off-by: Satyajit Desai <sadesai@codeaurora.org>