coresight-tpda: Add DSB dataset support

Read the DSB element size from the device tree. Set the register
bit that controls the DSB element size of the corresponding port.

Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/1695882586-10306-5-git-send-email-quic_taozha@quicinc.com