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_log.c b/common/cmd_log.c
index 6f8a27f..a03835d 100644
--- a/common/cmd_log.c
+++ b/common/cmd_log.c
@@ -252,7 +252,7 @@
 
 U_BOOT_CMD(
 	log,     255,	1,	do_log,
-	"log     - manipulate logbuffer\n",
+	"manipulate logbuffer",
 	"info   - show pointer details\n"
 	"log reset  - clear contents\n"
 	"log show   - show contents\n"