greybus: gpbridge: Add gpbridge driver init/exit helper macros

In order to help bridged-phy drivers to define init()/exit()
functions, define helper macro in gpbridge.h file.

Testing Done: Tested on gbsim.
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Tested-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

drivers/staging/greybus/gpbridge.h

@@ -56,6 +56,16 @@ void gb_gpbridge_deregister_driver(struct gpbridge_driver *driver);
 #define gb_gpbridge_deregister(driver) \
 	gb_gpbridge_deregister_driver(driver)
 
+#define gb_gpbridge_builtin_driver(__driver)		\
+	int __init gb_##__driver##_init(void)		\
+{							\
+	return gb_gpbridge_register(&__driver);		\
+}							\
+void gb_##__driver##_exit(void)				\
+{							\
+	gb_gpbridge_deregister(&__driver);			\
+}
+
 extern int gb_gpio_protocol_init(void);
 extern void gb_gpio_protocol_exit(void);