serial: 8250: Initialize fixed type fields when setting defaults

Prepare for 8250 split; move fixed type initialization into
serial8250_set_defaults(). This enables uart_config[] array to remain
file scope in base port operations after the split.

NB: the call to serial8250_init_fixed_type_port() from
serial8250_register_ports() was added by commit b5d228cc
("serial: copy UART properties of UPF_FIXED_TYPE ports provisioned
using early_serial_setup") specifically to support ports initialized
by early_serial_setup(). Since serial8250_set_defaults() is called
from early_serial_setup(), fixed type initialization is now already
handled there before serial8250_register_ports() is called.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>