Add initializer for 'mNoiseFloor' (#1708)
Add initializer for 'mNoiseFloor' (#1708)

* Add initializer for 'mNoiseFloor'

* Initialize class Mac's member variables in its constructor
lanyuwen/openthread,chshu/openthread,chshu/openthread,lanyuwen/openthread,erja-gp/openthread,gandreello/openthread,LeZhang2016/openthread,fbsder/openthread,xiaom-GitHub/openthread,pvanhorn/openthread,gandreello/openthread,erja-gp/openthread,vaas-krish/openthread,erja-gp/openthread,mszczodrak/openthread,vaas-krish/openthread,mszczodrak/openthread,chshu/openthread,georgecpr/openthread,srickardti/openthread,abtink/openthread,georgecpr/openthread,xiaom-GitHub/openthread,vaas-krish/openthread,LeZhang2016/openthread,chshu/openthread,gandreello/openthread,fbsder/openthread,jwhui/openthread,LeZhang2016/openthread,pvanhorn/openthread,mszczodrak/openthread,fbsder/openthread,JakubBrachTieto/openthread,turon/openthread,aeliot/openthread,georgecpr/openthread,jwhui/openthread,pvanhorn/openthread,erja-gp/openthread,aeliot/openthread,gandreello/openthread,librasungirl/openthread,lanyuwen/openthread,librasungirl/openthread,turon/openthread,librasungirl/openthread,georgecpr/openthread,turon/openthread,chshu/openthread,openthread/openthread,vaas-krish/openthread,LeZhang2016/openthread,aeliot/openthread,lanyuwen/openthread,xiaom-GitHub/openthread,mszczodrak/openthread,jwhui/openthread,srickardti/openthread,fbsder/openthread,chshu/openthread,openthread/openthread,openthread/openthread,bukepo/openthread,bukepo/openthread,erja-gp/openthread,JakubBrachTieto/openthread,LeZhang2016/openthread,xiaom-GitHub/openthread,librasungirl/openthread,fbsder/openthread,xiaom-GitHub/openthread,pvanhorn/openthread,abtink/openthread,fbsder/openthread,jwhui/openthread,aeliot/openthread,pvanhorn/openthread,aeliot/openthread,pvanhorn/openthread,srickardti/openthread,gandreello/openthread,mszczodrak/openthread,xiaom-GitHub/openthread,bukepo/openthread,georgecpr/openthread,lanyuwen/openthread,lanyuwen/openthread,vaas-krish/openthread,JakubBrachTieto/openthread,srickardti/openthread,mszczodrak/openthread,vaas-krish/openthread,bukepo/openthread,JakubBrachTieto/openthread,JakubBrachTieto/openthread,erja-gp/openthread,JakubBrachTieto/openthread,aeliot/openthread,LeZhang2016/openthread,gandreello/openthread,openthread/openthread,abtink/openthread,abtink/openthread,turon/openthread,georgecpr/openthread