drm/rockchip: Support AFBC on RK3399 big VOP

This patch adds preliminary support for hardware decode of Arm
Framebuffer Compression (AFBC) within the Rockchip display driver,
handled by the RK3399's big VOP. Combined with the open source Panfrost
userspace, this allows the on-board Mali GPU to compress framebuffers
in-flight across the chip from the GPU to the display driver, saving
considerable memory bandwidth.

This patch is based on the downstream ChromeOS patch to implement the
same functionality
https://chromium.googlesource.com/chromiumos/third_party/kernel/+/632d97fa4a1847eb489deee5bce6dcc04dd65fef

,
originally by Mark Yao with changes by Kristian H. Kristensen
<hoegsberg@chromium.org>. This patch allows the linked code to build
against a mainline kernel, using the standardized AFBC modifiers rather
than a ChromeOS specific modifier.

Signed-off-by: Mark Yao <mark.yao@rock-chips.com>
Signed-off-by: Alyssa Rosenzweig <alyssa@rosenzweig.io>