FROMLIST: 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);

Bug: 235550312
Link: https://lore.kernel.org/linux-scsi/20220614141655.14409-10-stanley.chu@mediatek.com/


Change-Id: I9990d2e5eb580f160b0c8b4a95b687d754d0767b
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>