Remove USB configurations and data structures from northbridge devicetree (SNB+MRC boards) and bootblock/romstage C code (native-only SNB boards). All USB configurations are drawn from southbridge devicetree going forward. Change-Id: Ie1cd21077136998a6e90050c95263f2efed68a67 Signed-off-by: Keith Hui <buurin@gmail.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/81882 Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>