mfd: lpc_ich: Fix resource request for [mem 0x00000000]

The older southbridges supported by the lpc_ich driver do not
provide memory-mapped space of the root complex. The driver
correctly avoids computing the iomem address in this case, yet
submits a zeroed resource request anyway (via mfd_add_devices()).

Remove the iomem resource from the resource array submitted to the
mfd core for the older southbridges.

Acked-by: Aaron Sierra <asierra@xes-inc.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>