qcom-common: Only include init.qcom.thermal_links.sh if needed

If we aren't installing any of the files that are used as the
destinations of the links then we shouldn't bother installing
the script that creates the links either.

Change-Id: I16495104c0ae44b35361f4b400e6fb9a19d6f3b1
Merge pull request #3 from omnirom/android-4.4

qcom-common: Only include init.qcom.thermal_links.sh if needed