x86, setup: Only set early_serial_base after port is initialized

putchar is using early_serial_base to check if port is initialized.

So we only assign it after early_serial_init() is called,
in case we need use VGA to debug early serial console.

Also add display for port addr and baud.

-v2: update to current tip

Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <4C3E0171.6050008@kernel.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>