scsi: ufs: Export regulator functions

Export below regulator functions to allow vendors to
customize regulator configuration in their own platforms.

int ufshcd_populate_vreg(struct device *dev, const char *name,
                         struct ufs_vreg **out_vreg);
int ufshcd_get_vreg(struct device *dev, struct ufs_vreg *vreg);

Link: https://lore.kernel.org/r/20220616053725.5681-10-stanley.chu@mediatek.com
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>