usb: gadget: Kconfig: fix typo for 'different'

Signed-off-by: Fabio Baltieri <fabio.baltieri@gmail.com>
Reviewed-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/usb/gadget/Kconfig

@@ -685,7 +685,7 @@ config USB_G_NCM
 	help
 	  This driver implements USB CDC NCM subclass standard. NCM is
 	  an advanced protocol for Ethernet encapsulation, allows grouping
-	  of several ethernet frames into one USB transfer and diffferent
+	  of several ethernet frames into one USB transfer and different
 	  alignment possibilities.
 
 	  Say "y" to link the driver statically, or "m" to build a