leds: ss4200: Fix the wrong format specifier for 'blinking'

The format specifier of "signed int" in sprintf() should be "%d", not
"%u".

Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20241111065809.3814-1-zhujun2@cmss.chinamobile.com


Signed-off-by: Lee Jones <lee@kernel.org>