configs: am57xx_evm: Enable DM_USB and DM_USB_DEV

Enable DM_USB and DM_USB_DEV for AM57xx based boards.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>