MIPS: dspr2: added optimizations for VP8YuvTo*

VP8YuvToRgb
VP8YuvToBgr
VP8YuvToRgb565
VP8YuvToRgba4444
VP8YuvToArgb
VP8YuvToBgra
VP8YuvToRgba

Change-Id: I22212a125d890e1fd28388fec906a1a5c07ff386
MIPS: mips32: code rebase

mips code rebased to be same as C code
from commit I8c29a8a0285076cb3423b01ffae9fcc465da6a81

Change-Id: I3848f4ce43387c3a62b336606498779f7b07ec44