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_irq.c b/common/cmd_irq.c
index a47cde4..a21aede 100644
--- a/common/cmd_irq.c
+++ b/common/cmd_irq.c
@@ -44,7 +44,7 @@
 
 U_BOOT_CMD(
 	interrupts, 5, 0, do_interrupts,
-	"interrupts - enable or disable interrupts\n",
+	"enable or disable interrupts",
 	"[on, off]\n"
 	"    - enable or disable interrupts\n"
 );