Initial support for Extreme Engineering Solutions XPedite5500 -
a P2020-based PMC/XMC single board computer.

Signed-off-by: John Schmoller <jschmoller@xes-inc.com>
Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>