nios2: add generic board support

This patch implements the generic board init as described in
doc/README.generic-board.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Signed-off-by: Scott McNutt <smcnutt@psyent.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/nios2/include/asm/config.h b/arch/nios2/include/asm/config.h
index cd29734..476a32b 100644
--- a/arch/nios2/include/asm/config.h
+++ b/arch/nios2/include/asm/config.h
@@ -7,4 +7,7 @@
 #ifndef _ASM_CONFIG_H_
 #define _ASM_CONFIG_H_
 
+#define CONFIG_SYS_GENERIC_BOARD
+#define CONFIG_SYS_GENERIC_GLOBAL_DATA
+
 #endif