drm/i915/gvt: use vgpu lock for active state setting

Need to align with deactivate, should only use vgpu's lock for
active state setting instead of gvt lock.

Fixes: f25a49ab ("drm/i915/gvt: Use vgpu_lock to protect per vgpu access")
Cc: Colin Xu <colin.xu@intel.com>
Reviewed-by: NColin Xu <colin.xu@intel.com>
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20191202070109.73924-2-zhenyuw@linux.intel.com

drivers/gpu/drm/i915/gvt/vgpu.c

@@ -212,9 +212,9 @@ static void intel_gvt_update_vgpu_types(struct intel_gvt *gvt)
  */
 void intel_gvt_activate_vgpu(struct intel_vgpu *vgpu)
 {
-	mutex_lock(&vgpu->gvt->lock);
+	mutex_lock(&vgpu->vgpu_lock);
 	vgpu->active = true;
-	mutex_unlock(&vgpu->gvt->lock);
+	mutex_unlock(&vgpu->vgpu_lock);
 }
 
 /**