MotionEvent: Avoid clipping tranformed orientation angle values

A recent refactor (ag/14556109) exposed an issue in the existing
orientation angle transformation logic where the output was clipped
incorrectly. There is no need to clip the ouput of atan2f because its
output is in the range [-pi, pi], which conforms to the MotionEvent's
orientation API.

Test: manual with stylus and test app
Bug: 202534592
Change-Id: I55df7470049922d0f579c2c1921dcacd0757ece1