[usb] support receiving ep data ready events without fetching data
[serial] use UART_RES instead of hard coding it. eventually this will not be a uart res
[serial] rename UART_RESOURCE_ID_BASE -> SERIAL_RESOURCE_ID_BASE
[serial] rename SERIAL_PREFIX->UART_PREFIX
[serial] use RES_MIN for UARTs in the SERIAL namespace
[serial] move definition of serial driver to serial_platform.h:
[serial] preparation for multiple serial drivers