cmd/led.c: fix typos in online help

Remove square brackets around label in state command description.

Fixes: ea41b156 ("cmd/led: check subcommand "list" instead "l"")
Signed-off-by: NAnatolij Gustschin <agust@denx.de>
Reviewed-by: NHeiko Schocher <hs@denx.de>

cmd/led.c

@@ -137,6 +137,6 @@ U_BOOT_CMD(
 	led, 4, 1, do_led,
 	"manage LEDs",
 	"<led_label> on|off|toggle" BLINK "\tChange LED state\n"
-	"led [<led_label>]\tGet LED state\n"
+	"led <led_label>\tGet LED state\n"
 	"led list\t\tshow a list of LEDs"
 );