MFC r254836, r254837:

drm: Support gem_open_object() and gem_close_object() callbacks

... in struct drm_driver_info.
MFC r254838:

drm: In drm_gem_name_create(), verify argument before acquiring lock

Submitted by:	J.R. Oldroyd <jr@opal.com>
MFC r254840:

drm: Use DRM_IF_MAJOR & DRM_IF_MINOR from drm_core.h
MFC r254841:

drm: Import list_for_each_entry_safe_from() macro
MFC r254848, r258930:

drm: Import drm_pcie_get_speed_cap_mask() in drm_pci.c

This comes with several PCI_VENDOR_ID_* defines which should go in a
more central place.