camera2: Undo mirror for front camera in legacy mode.

Bug: 16637957

- In Camera1 API, front facing camera preview is always mirrored across
  the vertical axis.  Undo this flip in the legacy mode Camera2 API
  sampling operation when copying from the texture drawn to with the
  Camera1 API preview buffers.

Change-Id: Ib8ae4fa97f4ad62a3e55ae7da7d474a8655e747d