scsi: ufs: Use the resource-managed function to add devfreq device

This patch uses the resource-managed to add the devfreq device.  This
function will make it easy to handle the devfreq device.

- struct devfreq *devm_devfreq_add_device(struct device *dev,
				  struct devfreq_dev_profile *profile,
				  const char *governor_name,
				  void *data);
Cc: Vinayak Holikatti <vinholikatti@gmail.com>
Cc: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>