coresight: etm4x: Update TRCIDR3.NUMPROCS handling to match v4.2

Since ETMv4.2, TRCIDR3.NUMPROCS has been extended to a 5bit field
by encoding the top 2 bits[4:3] in TRCIDR3.[13:12], which were RES0.
Fix the driver to compute the field correctly for ETMv4.2+

Cc: Mike Leach <mike.leach@linaro.org>
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>
Link: https://lore.kernel.org/r/20201127175256.1092685-6-mathieu.poirier@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>