payloads/external/SeaBIOS: Allow setting buffers below 0xC0000

Add the option to coreboot to set the SeaBIOS buffers below 0xC0000.
This is a requirement on the Intel Rangeley processor
because it is designed so that only the processor can write
the higher memory areas.  This prevents USB and SATA from bus-mastering
into the buffers when they're set in the typical 0xE0000 area.

This will be set to Y unless defaulted to N by the mainboard or
chipset.

Push the SeaBIOS buffers down to 0x90000 segment for Mohon Peak

Change-Id: I15638605d1c66a2277d4b852796db89978551a34
Signed-off-by: Martin Roth <martin.roth@se-eng.com>
Reviewed-on: http://review.coreboot.org/6364
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
mainboard/lenovo/t530: Make cdrom drive work by fixing devicetree

Change-Id: I804aff0fa53609e5fc70301053f075aa54b9bde5
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6893
Tested-by: build bot (Jenkins)
Reviewed-by: Idwer Vollering <vidwer@gmail.com>
mainboard/lenovo/t530: Enable PCIe Bridge for discrete graphics

Change-Id: I80f1e27268d0be58514d110611fd3c18cbe81829
Signed-off-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-on: http://review.coreboot.org/6895
Reviewed-by: Idwer Vollering <vidwer@gmail.com>
Tested-by: build bot (Jenkins)