x86, platform: Initial support for sta2x11 I/O hub

The "ConneXt" sta2x11 I/O Hub is a bridge from PCIe to AMBA, and is
used as main chipset in some Atom boards.  The set of peripherals it
exports live in an AMBA bus internal to the chip, so a custom
remapping of addresses is needed. This is implemented by fixup calls
for the PCI deivices, based on CONFIG_X86_DEV_DMA_OPS and
CONFIG_X86_DMA_REMAP .

Signed-off-by: Alessandro Rubini <rubini@gnudd.com>
Link: http://lkml.kernel.org/r/ddca670ca8180e52d49b3fe642742ddd23ab2cb2.1333560789.git.rubini@gnudd.com
Acked-by: Giancarlo Asnaghi <giancarlo.asnaghi@st.com>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>