ppc4xx: Convert lwmon5 board to generic board

Add CONFIG_SYS_GENERIC_BOARD to lwmon5.h and CONFIG_DISPLAY_BOARDINFO
to Kconfig file.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/board/lwmon5/Kconfig b/board/lwmon5/Kconfig
index 90566d8..7b8c605 100644
--- a/board/lwmon5/Kconfig
+++ b/board/lwmon5/Kconfig
@@ -6,4 +6,8 @@
 config SYS_CONFIG_NAME
 	default "lwmon5"
 
+config DISPLAY_BOARDINFO
+	bool
+	default y
+
 endif