v4l2_codec2: Adapt VideoPixelFormat code to Android standards.

This CL reworks the VideoPixelFormat class that was branched
from Chrome:
- Removed all Chrome-specific references from comments
- Removed specific numbering as we don't need compatibility with Chrome
- Removed deprecated formats
- Adhere to the Android coding style.
- Make use of Android logging mechanisms.
- Make use of Android assert macros.

Bug: 155138142
Test: arc.VideoEncodeAccel.h264_192p_i420_vm
Change-Id: I8387af0b427ebc990ec6374432f18ad732894569