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_dtt.c b/common/cmd_dtt.c
index c5b1d4d..7783c88 100644
--- a/common/cmd_dtt.c
+++ b/common/cmd_dtt.c
@@ -55,6 +55,6 @@
 
 U_BOOT_CMD(
 	  dtt,	1,	1,	do_dtt,
-	  "dtt     - Digital Thermometer and Thermostat\n",
+	  "Digital Thermometer and Thermostat",
 	  "        - Read temperature from digital thermometer and thermostat.\n"
 );