Command usage cleanup

Remove command name from all command "usage" fields and update
common/command.c to display "name - usage" instead of
just "usage". Also remove newlines from command usage fields.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
diff --git a/common/cmd_mii.c b/common/cmd_mii.c
index 19a7fbd..d70031a 100644
--- a/common/cmd_mii.c
+++ b/common/cmd_mii.c
@@ -453,7 +453,7 @@
 
 U_BOOT_CMD(
 	mii,	5,	1,	do_mii,
-	"mii     - MII utility commands\n",
+	"MII utility commands",
 	"device                     - list available devices\n"
 	"mii device <devname>           - set current device\n"
 	"mii info   <addr>              - display MII PHY info\n"