Fix nfs command help to reflect that the serverip is optional

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>

common/cmd_net.c

diff --git a/common/cmd_net.c b/common/cmd_net.c
index 21682c0..56eb684 100644
--- a/common/cmd_net.c
+++ b/common/cmd_net.c
@@ -87,7 +87,7 @@
 U_BOOT_CMD(
 	nfs,	3,	1,	do_nfs,
 	"nfs\t- boot image via network using NFS protocol\n",
-	"[loadAddress] [host ip addr:bootfilename]\n"
+	"[loadAddress] [[hostIPaddr:]bootfilename]\n"
 );
 #endif