We can determine if the pixel format used by the clients buffer is
scan-out capable much sooner, so do it when constructing the zpos
candidate list. It also removes the checks in their respective
prepare_ functions.
Avoids the situation where we'd need to retrieve the DRM framebuffer each time
when checking the pixel format.
Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
26dcce06d7