Removed "p" prefix lint rule

Summary: Android Studio only supports a single variable prefix for member variables. Having both the "m" prefix and the "p" prefix for member variables was causing automatic renaming and other things to not work correctly in Android Studio, so it is being removed. All non-static private and protected variables will now use the "m" prefix.

Test Plan: View unit test results.

Reviewers: mbishop, mportune, jstarke

Reviewed By: jstarke

Subscribers: mbishop

Differential Revision: https://devportal.imobile3.com/D11115