Refactor the restart logic by moving it into the function
adf_dev_restart() which uses the safe function adf_dev_up() and
adf_dev_down().

This commit does not implement any functional change.
Signed-off-by: Shashank Gupta <shashank.gupta@intel.com>
Reviewed-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>