I put my application folder in
packages/apps // inside AOSP source code
Now my application has following Android.mk in the s
Basically, the android AOSP build system doesn't build anything into /data. The idea of the /data partition is that it's user data, and that it will be shipped from the factory empty (and deleted entirely on a device reset). If you want to install something into /data you do it after install using "adb install" or any other mechanism.
What exactly are you trying to accomplish?