Moving the DRM driver structures from the middle of the PCI code to
the top of the file makes it more readable. Also remove an obsolete
comment.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200605135803.19811-9-tzimmermann@suse.de