sun4i_defconfig: build disp, hdmi and lcd into the kernel

- The majority of end-users wants to use the framebuffer, and all other options are aimed at that (e.g. G2D, Cedar,
  framebuffer memory reservation are all enabled by default)
- Previous problems that required building these options as modules instead of into the kernel no longer exist
  (since this commit: https://github.com/linux-sunxi/linux-sunxi/commit/199825c44a742fa0abd274948c5f66535b614fb7 )