leds: mt6323: Fix an off by one bug in probe

It should be ">= MT6323_MAX_LEDS" instead of ">".  Also "reg" is a u32
so it can't be negative and we can remove the test for negative values.

Fixes: 216ec6cc ("leds: Add LED support for MT6323 PMIC")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Jacek Anaszewski <jacek.anaszewski@gmail.com>