CHROMIUM: drm/rockchip: Add GEM create ioctl support

CHROMIUM: drm/rockchip: Add GEM create ioctl support

Rockchip Socs have GPU, we need allocate GPU accelerated buffers.
So add special ioctls GEM_CREATE/GEM_MAP_OFFSET to support
accelerated buffers.

Signed-off-by: Mark Yao <mark.yao@rock-chips.com>
BUG=chromium:399935
TEST=With rest of patch set, can boot to UI on eDP

Change-Id: Ia4b13798aac97d16214da7a75a2479e6e334313e
Reviewed-on: https://chromium-review.googlesource.com/222153
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>
Commit-Queue: Daniel Kurtz <djkurtz@chromium.org>
Conflicts:
	drivers/gpu/drm/rockchip/rockchip_drm_drv.c
(cherry picked from cros/chromeos-3.14 commit c29c5a3037e18815937d8af664738e499ada94d1)
Signed-off-by: ZhengShunQian <zhengsq@rock-chips.com>