Fixes for v5.6:
- Revert allow_fb_modifiers in sun4i, as it causes a regression for DE2 and DE3.
- Fix null pointer deref in drm_dp_mst_process_up_req().
Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/672810c3-4212-0a46-337b-2cb855573fd2@linux.intel.com