gvt-next-2017-12-14:

- fixes for two coverity scan errors (Colin)
- mmio switch code refine (Changbin)
- more virtual display dmabuf fixes (Tina/Gustavo)
- misc cleanups (Pei)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171214033434.jlppjlyal5d67ya7@zhen-hp.sh.intel.com