A series of cleanups / reorganizations and modesetting changes that
mostly target atomic state validation.

[airlied: conflicts with SPDX stuff in amdgpu tree]
Signed-off-by: Dave Airlie <airlied@redhat.com>

Link: https://patchwork.freedesktop.org/patch/msgid/1a88485e-e509-b00e-8485-19194f074115@vmware.com