arc: hard-code CONFIG_SYS_GENERIC_BOARD into asm/config.h

There're no other options for ARC except "generic board" so ther's no
point to define CONFIG_SYS_GENERIC_BOARD per board.

We now have it set fo all ARC boards.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/arch/arc/include/asm/config.h b/arch/arc/include/asm/config.h
index e5be078..c1e9b44 100644
--- a/arch/arc/include/asm/config.h
+++ b/arch/arc/include/asm/config.h
@@ -7,6 +7,7 @@
 #ifndef __ASM_ARC_CONFIG_H_
 #define __ASM_ARC_CONFIG_H_
 
+#define CONFIG_SYS_GENERIC_BOARD
 #define CONFIG_SYS_GENERIC_GLOBAL_DATA
 #define CONFIG_SYS_BOOT_RAMDISK_HIGH