platform: msm_shared: Cleanup mdp5 pipe select and flush code

1) Cleanup code repetition for pipe selection and flush using
   static functions.
2) Move pipe and mixer base address to target ipmap header file.
3) Combine switch cases for left and right pipes.

Change-Id: I1bda342dfab652742a207a3f934d9271a02e9e76
6 files changed