leds: lp5569: Use sysfs_emit instead of sprintf()

Replace sprintf() with sysfs_emit(), which is the modern standard for
formatting sysfs output.

This change aligng with the kernel's best practices and ensures usage of
the most up to date API.

Signed-off-by: Neel Bullywon <neelb2403@gmail.com>
Link: https://patch.msgid.link/20260207181825.13481-1-neelb2403@gmail.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: Nebu0528

drivers/leds/leds-lp5569.c

@@ -410,12 +410,12 @@ static ssize_t lp5569_selftest(struct device *dev,
 	/* Test LED Open */
 	pos = lp5569_led_open_test(led, buf);
 	if (pos < 0)
-		return sprintf(buf, "FAIL\n");
+		return sysfs_emit(buf, "FAIL\n");
 
 	/* Test LED Shorted */
 	pos += lp5569_led_short_test(led, buf);
 	if (pos < 0)
-		return sprintf(buf, "FAIL\n");
+		return sysfs_emit(buf, "FAIL\n");
 
 	for (i = 0; i < chip->pdata->num_channels; i++) {
 		/* Restore current */