Merge tag 'sunxi-drm-for-4.12' of https://git.kernel.org/pub/scm/linux/kernel/git/mripard/linux into drm-next

Allwinner DRM changes for 4.12

Not any functional changes, but a lot of preliminary rework in order to
support multiple display pipelines.

* tag 'sunxi-drm-for-4.12' of https://git.kernel.org/pub/scm/linux/kernel/git/mripard/linux: (26 commits)
  MAINTAINERS: Add sun4i-drm git repo
  drm/sun4i: Pass pointer for underlying backend into layer init
  drm/sun4i: Pass pointers for associated backend and tcon into crtc init
  drm/sun4i: tv: Get tcon and backend pointers from associated crtc
  drm/sun4i: Use embedded tcon pointer to get the tcon's output port node
  drm/sun4i: Fix tcon channel 0 comment about backporch = backporch + hsync
  drm/sun4i: Fix TCON clock and regmap initialization sequence
  drm/sun4i: Grab reserved memory region
  drm/sun4i: Add backend and tcon pointers to sun4i_crtc
  drm/sun4i: Add backend pointer to sun4i_layer
  drm/sun4i: rgb: Pass tcon pointer when initializing RGB encoder
  drm/sun4i: tv: Switch to drm_of_find_possible_crtcs
  drm/sun4i: Drop hardcoded .possible_crtcs values from layers
  drm/sun4i: Drop primary layer pointer from sun4i_drv
  drm/sun4i: Initialize crtc from tcon bind function
  drm/sun4i: Move layers from sun4i_drv to sun4i_crtc
  drm/sun4i: Add end of list element for sun4i_layers_init's returned list
  drm/sun4i: Set drm_crtc.port to the underlying TCON's output port node
  drm/sun4i: Make sunxi_rgb2yuv_coef constant
  drm/sun4i: Make sun4i_crtc_init return ERR_PTR style error codes
  ...