greybus: remove unused gb_connection_handler externs

Remove some leftover cruft from recent refactoring of
connection handlers.
Signed-off-by: Matt Porter <mporter@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/staging/greybus/greybus.h

@@ -252,12 +252,6 @@ void gb_gbuf_exit(void);
 extern struct bus_type greybus_bus_type;
 extern const struct attribute_group *greybus_module_groups[];
 
-extern struct gb_connection_handler gb_i2c_connection_handler;
-extern struct gb_connection_handler gb_gpio_connection_handler;
-extern struct gb_connection_handler gb_battery_connection_handler;
-extern struct gb_connection_handler gb_uart_connection_handler;
-extern struct gb_connection_handler gb_sdio_connection_handler;
-
 int gb_uart_device_init(struct gb_connection *connection);
 void gb_uart_device_exit(struct gb_connection *connection);