scsi: ufs: host: Hold reference returned by of_parse_phandle()

In ufshcd_populate_vreg(), we should hold the reference returned by
of_parse_phandle() and then use it to call of_node_put() for refcount
balance.

Link: https://lore.kernel.org/r/20220719071529.1081166-1-windhl@126.com
Fixes: aa497613

 ("ufs: Add regulator enable support")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Liang He <windhl@126.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>