build: Default to dtbToolCM

* The default dtbTool isn't the correct module name for the module that
  actually lives in device/qcom/common/dtbtool

Change-Id: I80b427e3652b99742573bc4d2829e51645a8822b
Merge remote-tracking branch 'mahdi/kk-4.4.3' into kk-4.4.3