Created a helper method that calculates the hotseat icons shift X.

Moved out logic that computes the translation X for the hotseat icons.

Fixes: 368379159
Test: Manual. Have the hotseat adjusted. Open any application from the
hotseat bar. Go back to home.
Flag: EXEMPT refactoring

Change-Id: If9dfa70be537f87b075bd865e7f9c5cd1ae78f00