usb: gadget: udc: atmel: Update Kconfig help for fifo_mode = 0

Update Kconfig help for fifo_mode = 0 to explain the behavior better.
Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/udc/Kconfig

@@ -62,8 +62,9 @@ config USB_ATMEL_USBA
 
 	  The fifo_mode parameter is used to select endpoint allocation mode.
 	  fifo_mode = 0 is used to let the driver autoconfigure the endpoints.
-	  In this case 2 banks are allocated for isochronous endpoints and
-	  only one bank is allocated for the rest of the endpoints.
+	  In this case, for ep1 2 banks are allocated if it works in isochronous
+	  mode and only 1 bank otherwise. For the rest of the endpoints
+	  only 1 bank is allocated.
 
 	  fifo_mode = 1 is a generic maximum fifo size (1024 bytes) configuration
 	  allowing the usage of ep1 - ep6