CHROMIUM: drm/rockchip: add GEM CPU acquire/release ioctls

CHROMIUM: drm/rockchip: add GEM CPU acquire/release ioctls

These ioctls can be used to synchronize CPU/GPU access to a buffer.

BUG=chrome-os-partner:33438
TEST=add CONFIG_DRM_DMA_SYNC=y, in conjunction with xf86-video-armsoc change,\
run any X application, like xev

Change-Id: I8065ec465ebd0cb6abe128a3e7d92a8f74a88928
Signed-off-by: Dominik Behr <dbehr@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/229441
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Conflicts:
	drivers/gpu/drm/rockchip/rockchip_drm_drv.c
	drivers/gpu/drm/rockchip/rockchip_drm_drv.h
	drivers/gpu/drm/rockchip/rockchip_drm_gem.c
(cherry picked from cros/chromeos-3.14 commit a847e1f492cbd186116c01a3f56575320dc87152)
Signed-off-by: ZhengShunQian <zhengsq@rock-chips.com>