drm/atomic: Move framebuffer checks to helper

Currently framebuffer checks happen directly in
drm_atomic_plane_check(). Move these checks into their own helper
method.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Acked-by: Sebastian Wick <sebastian@sebastianwick.net>
Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231027-solid-fill-v7-6-780188bfa7b2@quicinc.com