drm/i915/gvt: Introduce per object locking in GVT scheduler.

drm/i915/gvt: Introduce per object locking in GVT scheduler.

To support ww locking and per-object implemented in i915, GVT scheduler needs
to be refined. Most of the changes are located in shadow batch buffer, shadow
wa context in GVT-g, where use quite a lot of i915 gem object APIs.

v2:

- Adjust the usage of ww lock on context pin/unpin. (maarten)
- Rebase the patch on the newest staging branch.

Fixes: 6b05030496f7 ("drm/i915: Convert i915_gem_object/client_blt.c to use ww locking as well, v2.")
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Zhi Wang <zhi.a.wang@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1610314985-26065-1-git-send-email-zhi.wang.linux@gmail.com
Reviewed-by: Zhenyu Wang <zhenyuw@linux.intel.com>