at91: add support for RSIs EWS board

This adds support for the RSI EWS machine (at91rm9200-based),
machine type 1609.

Includes fixes as suggested by Uwe Kleine-König and
cleanups as suggested by Russell and R.Schwebel.

Signed-off-by: Josef Holzmayr <holzmayr@rsi-elektrotechnik.de>
[nicolas.ferre@atmel.com: simplify board file header, move to at91_init_irq_default]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
diff --git a/arch/arm/mach-at91/Makefile b/arch/arm/mach-at91/Makefile
index bf57e8b..ecd6479 100644
--- a/arch/arm/mach-at91/Makefile
+++ b/arch/arm/mach-at91/Makefile
@@ -36,6 +36,7 @@
 obj-$(CONFIG_MACH_YL9200)	+= board-yl-9200.o
 obj-$(CONFIG_MACH_CPUAT91)	+= board-cpuat91.o
 obj-$(CONFIG_MACH_ECO920)	+= board-eco920.o
+obj-$(CONFIG_MACH_RSI_EWS)	+= board-rsi-ews.o
 
 # AT91SAM9260 board-specific support
 obj-$(CONFIG_MACH_AT91SAM9260EK) += board-sam9260ek.o