gpu: ion: Increment the ref count in mmap

The refcount increment actually needs to happen in mmap.
Otherwise it doesn't actually happen.

Change-Id: I1043453c2c828b8658a28acea57181759b2b21f0
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
diff --git a/drivers/gpu/ion/ion.c b/drivers/gpu/ion/ion.c
index 34145fe..386593f5 100644
--- a/drivers/gpu/ion/ion.c
+++ b/drivers/gpu/ion/ion.c
@@ -1315,12 +1315,14 @@
 	/* now map it to userspace */
 	ret = buffer->heap->ops->map_user(buffer->heap, buffer, vma,
 						flags);
-	mutex_unlock(&buffer->lock);
+
+	buffer->umap_cnt++;
 	if (ret) {
 		pr_err("%s: failure mapping buffer to userspace\n",
 		       __func__);
 		goto err2;
 	}
+	mutex_unlock(&buffer->lock);
 
 	vma->vm_ops = &ion_vm_ops;
 	/* move the handle into the vm_private_data so we can access it from
@@ -1335,6 +1337,7 @@
 
 err2:
 	buffer->umap_cnt--;
+	mutex_unlock(&buffer->lock);
 	/* drop the reference to the handle */
 err1:
 	ion_handle_put(handle);