ARM: orion5x: switch to preprocessor includes in DT

This commit switches the Orion5x Device Tree files to use C
preprocessor based includes, as it will allow us to use definitions
from header files in future commits.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1398202002-28530-12-git-send-email-thomas.petazzoni@free-electrons.com
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>