scsi: ufs: remove unnecessary pointer evaluation

The pointer value is initialized as &hba->vreg_info, and it's never
changed. It's not necessary to check the pointer is null or not.

Signed-off-by: Zeng Guangyue <zengguangyue@hisilicon.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>