at91: rename rm9200ek and rm9200dk board file name

to be a few more concistant with the other boards

as ek is for evaluation kit and dk for development kit

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Andrew Victor <linux@maxim.org.za>
3 files changed