staging: greybus: move core include files to include/linux/greybus/

With the goal of moving the core of the greybus code out of staging, the
include files need to be moved to include/linux/greybus.h and
include/linux/greybus/

Cc: Vaibhav Hiremath <hvaibhav.linux@gmail.com>
Cc: Johan Hovold <johan@kernel.org>
Cc: Vaibhav Agarwal <vaibhav.sr@gmail.com>
Cc: Rui Miguel Silva <rmfrfs@gmail.com>
Cc: David Lin <dtwlin@gmail.com>
Cc: "Bryan O'Donoghue" <pure.logic@nexus-software.ie>
Cc: greybus-dev@lists.linaro.org
Cc: devel@driverdev.osuosl.org
Acked-by: Mark Greer <mgreer@animalcreek.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Alex Elder <elder@kernel.org>
Link: https://lore.kernel.org/r/20190825055429.18547-8-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/greybus/module.h

@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Greybus Module code
+ *
+ * Copyright 2016 Google Inc.
+ * Copyright 2016 Linaro Ltd.
+ */
+
+#ifndef __MODULE_H
+#define __MODULE_H
+
+struct gb_module {
+	struct device dev;
+	struct gb_host_device *hd;
+
+	struct list_head hd_node;
+
+	u8 module_id;
+	size_t num_interfaces;
+
+	bool disconnected;
+
+	struct gb_interface *interfaces[0];
+};
+#define to_gb_module(d) container_of(d, struct gb_module, dev)
+
+struct gb_module *gb_module_create(struct gb_host_device *hd, u8 module_id,
+				   size_t num_interfaces);
+int gb_module_add(struct gb_module *module);
+void gb_module_del(struct gb_module *module);
+void gb_module_put(struct gb_module *module);
+
+#endif /* __MODULE_H */