SBL doesn't support 40-pin header for now, so the serial PCI
device(0:18:1) on it doesn't work. Let's just workaround this by
changing hv's default serial output device to 0:18:0. In the future,
we'd rather change it back if SBL supports it.
This change is only for SBL, for UEFI, now we offer serial configuration
through command line parameter(vuart=...).
Tracked-On: #1995
Signed-off-by: Tw <wei.tan@intel.com>
Reviewed-by: Binbin Wu <binbin.wu@intel.com>