ARM: at91: at91_dt_defconfig: remove CONFIG_USB_AT91

Remove CONFIG_USB_AT91 at is not used on 9x5 or 9x60 boards.

Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com>

Author: cristibirsan

arch/arm/configs/at91_dt_defconfig

@@ -188,7 +188,6 @@ CONFIG_USB_SERIAL_GENERIC=y
 CONFIG_USB_SERIAL_FTDI_SIO=y
 CONFIG_USB_SERIAL_PL2303=y
 CONFIG_USB_GADGET=y
-CONFIG_USB_AT91=m
 CONFIG_USB_ATMEL_USBA=m
 CONFIG_USB_CONFIGFS=m
 CONFIG_USB_CONFIGFS_ACM=y