leds: is31fl319x: Fix devm vs. non-devm ordering

When non-devm resources are allocated they mustn't be followed by
devm allocations, otherwise it will break the tear down ordering
and might lead to crashes or other bugs during ->remove() stage.
Fix this by wrapping mutex_destroy() call with
devm_add_action_or_reset().

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
Signed-off-by: Pavel Machek <pavel@ucw.cz>