drm/msm: change gem->vmap() to get/put

Before we can add vmap shrinking, we really need to know which vmap'ings
are currently being used.  So switch to get/put interface.  Stubbed put
fxns for now.

Signed-off-by: Rob Clark <robdclark@gmail.com>
diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c
index 42f5359..f326cf6 100644
--- a/drivers/gpu/drm/msm/msm_ringbuffer.c
+++ b/drivers/gpu/drm/msm/msm_ringbuffer.c
@@ -39,7 +39,7 @@
 		goto fail;
 	}
 
-	ring->start = msm_gem_vaddr_locked(ring->bo);
+	ring->start = msm_gem_get_vaddr_locked(ring->bo);
 	if (IS_ERR(ring->start)) {
 		ret = PTR_ERR(ring->start);
 		goto fail;
@@ -59,7 +59,9 @@
 
 void msm_ringbuffer_destroy(struct msm_ringbuffer *ring)
 {
-	if (ring->bo)
+	if (ring->bo) {
+		msm_gem_put_vaddr(ring->bo);
 		drm_gem_object_unreference_unlocked(ring->bo);
+	}
 	kfree(ring);
 }