Update AOSP tracking tag to 4.4.4_r2

This commit switches the tracked repositories for flo to use 4.4.4_r2
instead of the older 4.4.3_r1.1 that was used before.

Change-Id: Ia5ea49b8a6b5b70a77fef2186d6cb16250f783d7
Merge pull request #1 from vedantgp/kitkat

Update AOSP tracking tag to 4.4.4_r2