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/Kconfig b/arch/arm/mach-at91/Kconfig
index 2248467..1555c55 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -182,6 +182,11 @@
 	help
 	  Select this if you are using the eco920 board
 
+config MACH_RSI_EWS
+	bool "RSI Embedded Webserver"
+	depends on ARCH_AT91RM9200
+	help
+	  Select this if you are using RSIs EWS board.
 endif
 
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