drm: Remove source code for non-KMS drivers

Remove all remaining source code for non-KMS drivers. These drivers
have been removed in v6.3 and won't comeback.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: David Airlie <airlied@gmail.com>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231122122449.11588-13-tzimmermann@suse.de