coresight tmc etr: Setup AXI cache encoding for read transfers

If the ETR supports split cache encoding (i.e, separate bits for
read and write transfers) unlike the older version (where read
and write transfers use the same encoding in AXICTL[2-5]).
This feature is not advertised and has to be described by the
static mask associated with the device id.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>