USB: gadget: f_fs: functionfs_add() renamed to functionfs_bind_config()

FunctionFS had a bit unique name for function used to add it
to USB configuration.  Renamed as to match naming convention
of other functions.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/usb/gadget/g_ffs.c b/drivers/usb/gadget/g_ffs.c
index d1af253..da3a9e4 100644
--- a/drivers/usb/gadget/g_ffs.c
+++ b/drivers/usb/gadget/g_ffs.c
@@ -388,7 +388,7 @@
 			return ret;
 	}
 
-	ret = functionfs_add(c->cdev, c, gfs_ffs_data);
+	ret = functionfs_bind_config(c->cdev, c, gfs_ffs_data);
 	if (unlikely(ret < 0))
 		return ret;