Added support for the Iskratel XCEP single board computer, embedded in
instruments used in particle accelerators.

The patch contains the platform specific code, Makefile and Kconfig
changes for platform arm-pxa.
Signed-off-by: Aleš Bardorfer <ales.bardorfer@i-tech.si>
Signed-off-by: Michael Abbott <michael.abbott@diamond.ac.uk>
Signed-off-by: Matej Kenda <matej.kenda@i-tech.si>
Signed-off-by: Eric Miao <eric.y.miao@gmail.com>