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_mac.c b/common/cmd_mac.c
index 4453299..cf601e4 100644
--- a/common/cmd_mac.c
+++ b/common/cmd_mac.c
@@ -28,7 +28,7 @@
 
 U_BOOT_CMD(
 	mac, 3, 1,  do_mac,
-	"mac     - display and program the system ID and MAC addresses in EEPROM\n",
+	"display and program the system ID and MAC addresses in EEPROM",
 	"[read|save|id|num|errata|date|ports|0|1|2|3|4|5|6|7]\n"
 	"read\n"
 	"    - show content of EEPROM\n"