ZOOM2 Add serial support.

Zoom2 serial is in general supplied by one of the 4 UARTS on the debug board.
The default serial is from the USB connector on left side of the debug board.
The USB connector will produce 2 of the 4 UARTS.  On your host pick the first
enumeration.

The details of the setting of the serial gpmc setup are not available.
The values were provided by another party.

The serial port set up is the same with Zoom1.
Baud rate 115200, 8 bit data, no parity, 1 stop bit, no flow.

The kernel bootargs are
console=ttyS3,115200n8

Signed-off-by: Tom Rix <Tom.Rix@windriver.com>