drm/bochs: Pass bochs device to various functions

Avoid upcasting from struct drm_device by passing the bochs device
directly to functions.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240902105546.792625-5-tzimmermann@suse.de