xilinx: Show silicon version in SPL

Both Zynq and ZynqMP can show silicon versions in SPL boot flow. It is
useful to be aware.
The patch is also fixing possition of these bits on ZynqMP.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
diff --git a/board/xilinx/zynq/board.c b/board/xilinx/zynq/board.c
index 7ac069a..0fc11a4 100644
--- a/board/xilinx/zynq/board.c
+++ b/board/xilinx/zynq/board.c
@@ -24,6 +24,9 @@
 
 int board_init(void)
 {
+	if (IS_ENABLED(CONFIG_SPL_BUILD))
+		printf("Silicon version:\t%d\n", zynq_get_silicon_version());
+
 	return 0;
 }