at91: add support for the PM9261 board of Ronetix GmbH

The PM9261 board is based on the AT91SAM9261-EK board.

Here is the page on Ronetix website:
http://www.ronetix.at/starter_kit_9261.html

Signed-off-by: Ilko Iliev <iliev@ronetix.at>
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/Makefile b/Makefile
index bcc81c9..eb58dfe 100644
--- a/Makefile
+++ b/Makefile
@@ -2782,6 +2782,9 @@
 	fi;
 	@$(MKCONFIG) -a at91sam9rlek arm arm926ejs at91sam9rlek atmel at91
 
+pm9261_config	:	unconfig
+	@$(MKCONFIG) $(@:_config=) arm arm926ejs pm9261 ronetix at91
+
 pm9263_config	:	unconfig
 	@$(MKCONFIG) $(@:_config=) arm arm926ejs pm9263 ronetix at91