unify version_string

This patch removes the architecture specific implementation of
version_string where possible. Some architectures use a special place
and therefore we provide U_BOOT_VERSION_STRING definition and a common
weak symbol version_string.

Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
CC: Mike Frysinger <vapier@gentoo.org>
CC: Peter Pan <pppeterpppan@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/include/version.h b/include/version.h
index a34291a..ec4e1f8 100644
--- a/include/version.h
+++ b/include/version.h
@@ -24,8 +24,19 @@
 #ifndef	__VERSION_H__
 #define	__VERSION_H__
 
+#include <timestamp.h>
+
 #ifndef DO_DEPS_ONLY
 #include "version_autogenerated.h"
 #endif
 
+#ifndef CONFIG_IDENT_STRING
+#define CONFIG_IDENT_STRING ""
+#endif
+
+#define U_BOOT_VERSION_STRING U_BOOT_VERSION " (" U_BOOT_DATE " - " \
+	U_BOOT_TIME ")" CONFIG_IDENT_STRING
+
+extern const char version_string[];
+
 #endif	/* __VERSION_H__ */