drm/msm/sde: use new format list for virtual VIG pipes

Add a new format list specifically for virtual ViG pipes since
virtual ViG pipes might not support all the formats specified
by the previously used dma_formats list.

Change-Id: Ibf46e8e01d3afe1b24e1be2d801b998cb28d4672
Signed-off-by: Steve Cohen <cohens@codeaurora.org>