drm/msm: Add priv->mm_lock to protect active/inactive lists

Rather than relying on the big dev->struct_mutex hammer, introduce a
more specific lock for protecting the bo lists.

Change-Id: I4c876a1c3ae51ff62372703a99a8daff0c4a7950
Signed-off-by: Rob Clark <robdclark@chromium.org>
Git-commit: d984457b31c4c53d2af374d5e78b3eb64debd483
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
[samtran@codeaurora.org: avoid changes related to debugfs and shrinker]
Signed-off-by: Samantha Tran <samtran@codeaurora.org>

msm/msm_drv.c

@@ -798,6 +798,7 @@ static int msm_drm_component_init(struct device *dev)
 	INIT_LIST_HEAD(&priv->client_event_list);
 	INIT_LIST_HEAD(&priv->inactive_list);
 	INIT_LIST_HEAD(&priv->vm_client_list);
+	mutex_init(&priv->mm_lock);
 
 	mutex_init(&priv->vm_client_lock);