[bugfix]fix some bug of DMI mapper of modbus#96

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RyanZhaoXB wants to merge 3 commits intokubeedge:mainfrom RyanZhaoXB:DMI-bugfix

+210-45

Commits on Mar 13, 2023

bugfix: fix bug for nil pointer of twin and context thread block
RyanZhaoXB
committed
do not report if the twin data is not changed to prevent triggering traffic limiting
RyanZhaoXB
committed

Commits on Mar 14, 2023

update log level, update collectCycle with time.Second and support twin for string, bool and float type
RyanZhaoXB
committed