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_onenand.c b/common/cmd_onenand.c
index 6d43a77..5832ff8 100644
--- a/common/cmd_onenand.c
+++ b/common/cmd_onenand.c
@@ -471,7 +471,7 @@
 
 U_BOOT_CMD(
 	onenand,	6,	1,	do_onenand,
-	"onenand - OneNAND sub-system\n",
+	"OneNAND sub-system",
 	"info - show available OneNAND devices\n"
 	"onenand bad - show bad blocks\n"
 	"onenand read[.oob] addr off size\n"