add net5501 support

add net5501 support

This patch brings up the net5501 platform.

Note that the x86/ target included support for all x86/ class
processors.  That's not technically correct.  This should be constrained
only to the "generic" subtarget.  Every x86-class target that isn't
generic should be able to select only the optimizations/capabilities
applicable to that architectural variant.

It's also assumed that all x86 processors have keyboard & mouse ports,
ISA, DMI, ACPI... the embedded ones typically don't.  Again, moving
that to the generic subtarget.

Fortunately, this was a fairly benign tweak.

The net5501 board includes the following logic:

Geode/LX processor
CS5535 super-I/O chip
PC87360 sensor chip
Via Rhine Ethernet controllers
Via Sata controllers
USB, LEDS, I2C

Signed-off-by: Philip Prindeville <philipp_subx@redfish-solutions.com>
SVN-Revision: 20794