The denoiser was writing to LAST_FRAME buffer.   If LAST_FRAME isn't being
updated,  the reference frame buffers were out of sync between the encoder and the
denoised raw buffers. This patch resolves the discrepancy by always writing to a work
buffer (INTRA_FRAME) and then copying from that buffer to any buffers that needs to
be updated.

Change-Id: I6dd855b9749978b542bc3d515914d5f16faf25df