vaapipostproc: if dmabuf then disable deinterlace
Submitted by Víctor Manuel Jáquez Leal
dmabuf can contain interlaced content, but, as far as I understand, the sink
should have the mechanism to deinterlace dmabuf-based buffers. For example,
when using EGL_EXT_image_dma_buf_import, two EGLImages should be generated
from one dmabuf-based buffer.