hwmon: (cros_ec) Fix access to restricted __le16

0-day complains:

drivers-hwmon-cros_ec_hwmon.c:sparse:sparse:cast-to-restricted-__le16

Fix by using a __le16 typed variable as parameter to le16_to_cpu().

Fixes: bc3e4525 ("hwmon: add ChromeOS EC driver")
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20240606180507.3332237-1-linux@roeck-us.netSigned-off-by: Tzung-Bi Shih <tzungbi@kernel.org>

drivers/hwmon/cros_ec_hwmon.c

@@ -26,12 +26,13 @@ struct cros_ec_hwmon_priv {
 static int cros_ec_hwmon_read_fan_speed(struct cros_ec_device *cros_ec, u8 index, u16 *speed)
 {
 	int ret;
+	__le16 __speed;
 
-	ret = cros_ec_cmd_readmem(cros_ec, EC_MEMMAP_FAN + index * 2, 2, speed);
+	ret = cros_ec_cmd_readmem(cros_ec, EC_MEMMAP_FAN + index * 2, 2, &__speed);
 	if (ret < 0)
 		return ret;
 
-	*speed = le16_to_cpu(*speed);
+	*speed = le16_to_cpu(__speed);
 	return 0;
 }