ppc: xilinx-ppc: Move to generic board support

Generic board support seems to work just fine. Tested on ml507 with
bitstream generated on the latest ISE software.

Tested-by: Georg Schardt <schardt@team-ctech.de>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>

include/configs/xilinx-ppc.h

@@ -11,6 +11,9 @@
 
 #ifndef __CONFIG_XLX_H
 #define __CONFIG_XLX_H
+
+#define CONFIG_SYS_GENERIC_BOARD
+
 /*
 #define DEBUG
 #define ET_DEBUG