driver core: fw_devlink_relax_cycle() can be static

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20201218063934.GA66003@e60698be8304


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>