platform/mellanox: mlxreg-hotplug: use sysfs_emit() instead of sprintf()

Follow the advice in Documentation/filesystems/sysfs.rst:
show() should only use sysfs_emit() or sysfs_emit_at() when formatting
the value to be returned to user space.

Signed-off-by: Ai Chao <aichao@kylinos.cn>
Acked-by: Vadim Pasternak <vadimp@nvidia.com>
Link: https://lore.kernel.org/r/20250116081000.2900435-1-aichao@kylinos.cn
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: TomAi0

drivers/platform/mellanox/mlxreg-hotplug.c

@@ -232,7 +232,7 @@ static ssize_t mlxreg_hotplug_attr_show(struct device *dev,
 			regval = !!(regval & data->mask);
 	}
 
-	return sprintf(buf, "%u\n", regval);
+	return sysfs_emit(buf, "%u\n", regval);
 }
 
 #define PRIV_ATTR(i) priv->mlxreg_hotplug_attr[i]