coresight-tpdm: Optimize the store function of tpdm simple dataset

Replace spin lock/unlock to avoid forgetting to unlock when the
function exits. And refine methods for handling various conditions.

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/1707024641-22460-2-git-send-email-quic_taozha@quicinc.com