leds: leds-cros_ec: Skip LEDs without color components

A user reports that on their Lenovo Corsola Magneton with EC firmware
steelix-15194.270.0 the driver probe fails with EINVAL. It turns out
that the power LED does not contain any color components as indicated
by the following "ectool led power query" output:

Brightness range for LED 1:
        red     : 0x0
        green   : 0x0
        blue    : 0x0
        yellow  : 0x0
        white   : 0x0
        amber   : 0x0

The LED also does not react to commands sent manually through ectool and
is generally non-functional.

Instead of failing the probe for all LEDs managed by the EC when one
without color components is encountered, silently skip those.

Cc: stable@vger.kernel.org
Fixes: 8d6ce6f ("leds: Add ChromeOS EC driver")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20251028-cros_ec-leds-no-colors-v1-1-ebe13a02022a@weissschuh.net
Signed-off-by: Lee Jones <lee@kernel.org>

Author: t-8ch

drivers/leds/leds-cros_ec.c

@@ -142,9 +142,6 @@ static int cros_ec_led_count_subleds(struct device *dev,
 		}
 	}
 
-	if (!num_subleds)
-		return -EINVAL;
-
 	*max_brightness = common_range;
 	return num_subleds;
 }
@@ -189,6 +186,8 @@ static int cros_ec_led_probe_one(struct device *dev, struct cros_ec_device *cros
 						&priv->led_mc_cdev.led_cdev.max_brightness);
 	if (num_subleds < 0)
 		return num_subleds;
+	if (num_subleds == 0)
+		return 0; /* LED without any colors, skip */
 
 	priv->cros_ec = cros_ec;
 	priv->led_id = id;