drm/hisilicon/hibmc: Add hisilicon hibmc drm master driver

Add DRM master driver for Hisilicon Hibmc SoC which used for
Out-of-band management. Blow is the general hardware connection,
both the Hibmc and the host CPU are on the same mother board.

+----------+       +----------+
|          | PCIe  |  Hibmc   |
|host CPU( |<----->| display  |
|arm64,x86)|       |subsystem |
+----------+       +----------+

Signed-off-by: Rongrong Zou <zourongrong@gmail.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Reviewed-by: Xinliang Liu <xinliang.liu@linaro.org>
Acked-by: Sean Paul <seanpaul@chromium.org>