cmd_net.c: fix build breakage

Commit 722b061 "autocomplete: remove runtime handler install" caused
some boards (like NETTA2_V2) to break with errors like these:

cmd_net.c:296: error: expected expression before ',' token

Fix this.

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Mike Frysinger <vapier@gentoo.org>
diff --git a/common/cmd_net.c b/common/cmd_net.c
index 973fa21..00e0ea8 100644
--- a/common/cmd_net.c
+++ b/common/cmd_net.c
@@ -296,6 +296,7 @@
 U_BOOT_CMD(
 	cdp,	1,	1,	do_cdp,
 	"Perform CDP network configuration",
+	"\n"
 );
 #endif