nds32/board.c: add PCI prompt at boot up

add PCI prompt at boot up for probing PCI device

Signed-off-by: Macpaul Lin <macpaul@andestech.com>
diff --git a/arch/nds32/lib/board.c b/arch/nds32/lib/board.c
index 66e4537..074aabf 100644
--- a/arch/nds32/lib/board.c
+++ b/arch/nds32/lib/board.c
@@ -365,6 +365,7 @@
 	env_relocate();
 
 #if defined(CONFIG_CMD_PCI) || defined(CONFIG_PCI)
+	puts("PCI:   ");
 	nds32_pci_init();
 #endif