include/drm: sync up drm.h

a) delta: Adds DRM_IOCTL_MODE_GETFB2
  b) Generated using make headers_install
  c) Taken from drm-next-misc:
        commit 3ff4c24bdb1f494c217c80348f9db4896043ed81
        Author: Lyude Paul <lyude@redhat.com>
        Date:   Fri Jan 17 17:47:48 2020 -0500

        drm/dp_mst: Fix indenting in drm_dp_mst_topology_mgr_set_mst()

Signed-off-by: Juston Li <juston.li@intel.com>
Acked-by: Eric Engestrom <eric@engestrom.ch>