One-pass rate control cleanups/fixes/refactoring

Inlcudes a number cleanups:
1. Moves the one-pass pre-encode parameter setting functions
to vp9_ratectrl.c
2. Deprecates per_frame_bandwidth in RATE_CONTROL structure
3. Removes target_bandwidth in cpi structure since it is not used.
4. Various renaming of functions

There is no bit-stream change in 2-pass, one-pass cbr and one-pass
vbr modes.

Change-Id: Ifd9916bf4d485b7d04c5f52044ffe6703254ccbd