[PATCH] Disable integrated Intel 3100 devices properly

[Ed Swierk]

Setting an integrated southbridge device (like SATA or USB2.0) to
"off" in Config.lb should cause the PCI device not to respond to
configuration requests. The code that takes care of this for the Intel
3100 is in src/southbridge/intel/i3100/i3100.c. Unfortunately I copied
the esb6300 implementation without noticing that it makes no sense at
all on the Intel 3100. The attached patch implements this properly for
the Intel 3100.

--Ed