drm: Centralize format information

Various pieces of information about DRM formats (number of planes, color
depth, chroma subsampling, ...) are scattered across different helper
functions in the DRM core. Callers of those functions often need to
access more than a single parameter of the format, leading to
inefficiencies due to multiple lookups.

Centralize all format information in a data structure and create a
function to look up information based on the format 4CC.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Eric Engestrom <eric.engestrom@imgtec.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1476744081-24485-2-git-send-email-laurent.pinchart@ideasonboard.com