scsi: ufs: ufs-mediatek: Fix the timing of configuring device regulators

Currently the LPM configurations of device regulators may not work since
VCC is not disabled yet while ufs_mtk_vreg_set_lpm() is executed.

Fix this by changing the timing of invoking ufs_mtk_vreg_set_lpm().

Link: https://lore.kernel.org/r/20220616053725.5681-5-stanley.chu@mediatek.com
Reviewed-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Po-Wen Kao <powen.kao@mediatek.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>