coresight-tpdm: Correct the property name of MSR number

Correct the property name of the DSB MSR number that needs to be
read in TPDM driver. The right property name is
"qcom,dsb-msrs-num".

Fixes: 350ba15a ("coresight-tpdm: Add nodes for dsb msr support")
Signed-off-by: Tao Zhang <quic_taozha@quicinc.com>
[ Fix checkpatch failure in the commit description ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/1698128353-31157-1-git-send-email-quic_taozha@quicinc.com