coresight-tpdm: Add CMB dataset support

CMB (continuous multi-bit) is one of TPDM's dataset type. CMB subunit
can be enabled for data collection by writing 1 to the first bit of
CMB_CR register. This change is to add enable/disable function for
CMB dataset by writing CMB_CR register.

Reviewed-by: James Clark <james.clark@arm.com>
Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
Signed-off-by: Jinlong Mao <quic_jinlmao@quicinc.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/1707024641-22460-5-git-send-email-quic_taozha@quicinc.com