at91: reworked support for otc570 board

The otc570 board support was broken. Within this opportunity, I completely
reworked the board files.

Signed-off-by: Daniel Gorsulowski <Daniel.Gorsulowski@esd.eu>
diff --git a/boards.cfg b/boards.cfg
index 4962e04..01c620e 100644
--- a/boards.cfg
+++ b/boards.cfg
@@ -88,7 +88,8 @@
 top9000su_xe                 arm         arm926ejs   top9000             emk            at91        top9000:SU9000
 meesc                        arm         arm926ejs   meesc               esd            at91        meesc:AT91SAM9263,SYS_USE_NANDFLASH
 meesc_dataflash              arm         arm926ejs   meesc               esd            at91        meesc:AT91SAM9263,SYS_USE_DATAFLASH
-otc570                       arm         arm926ejs   -                   esd            at91
+otc570                       arm         arm926ejs   otc570              esd            at91        otc570:AT91SAM9263,SYS_USE_NANDFLASH
+otc570_dataflash             arm         arm926ejs   otc570              esd            at91        otc570:AT91SAM9263,SYS_USE_DATAFLASH
 pm9261                       arm         arm926ejs   -                   ronetix        at91
 pm9263                       arm         arm926ejs   -                   ronetix        at91
 da830evm                     arm         arm926ejs   da8xxevm            davinci        davinci