qcom-common: Drop local copy of dtbTool for dtbToolCM

* dtbToolCM supports both v1 and v2, and resides in
  CyanogenMod/android_device_qcom_common

This reverts commit 94edd40ca4f6a87d0ee6150060d8d4baf2636400.

Change-Id: I001f163985c2f1fe38e061f2a5ebad42656b6eda