gpu: host1x: Export public API

Make the public API symbols visible so that depending drivers can be
built as a module.

Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/drivers/gpu/host1x/bus.c b/drivers/gpu/host1x/bus.c
index 6a92959..ccdd2e6 100644
--- a/drivers/gpu/host1x/bus.c
+++ b/drivers/gpu/host1x/bus.c
@@ -188,6 +188,7 @@
 
 	return 0;
 }
+EXPORT_SYMBOL(host1x_device_init);
 
 int host1x_device_exit(struct host1x_device *device)
 {
@@ -213,6 +214,7 @@
 
 	return 0;
 }
+EXPORT_SYMBOL(host1x_device_exit);
 
 static int host1x_register_client(struct host1x *host1x,
 				  struct host1x_client *client)