gizmosphere/gizmo: Change the PCIe GPP to two x1 ports

Gizmo sends two southbridge GPP PCIe lanes to its high speed
edge connector. This change will allow developers to create
two x1 slots on an extender card.

Change-Id: Iba6c1a4caf7846d12e3960775d7bc906ca8ff385
Signed-off-by: Dave Frodin <dave.frodin@se-eng.com>
Reviewed-on: http://review.coreboot.org/6499
Tested-by: build bot (Jenkins)
Reviewed-by: Edward O'Callaghan <eocallaghan@alterapraxis.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>