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/board/amcc/luan/luan.c b/board/amcc/luan/luan.c
index e1357f4..d2a3b9e 100644
--- a/board/amcc/luan/luan.c
+++ b/board/amcc/luan/luan.c
@@ -329,7 +329,7 @@
 
 U_BOOT_CMD(
 	l2cache,   2,   1,     do_l2cache,
-	"l2cache  - enable or disable L2 cache\n",
+	"enable or disable L2 cache",
 	"[on, off]\n"
 	"    - enable or disable L2 cache\n"
 	);