UPSTREAM: scsi: ufs-mediatek: Fix imprecise waiting time for ref-clk control

Currently ref-clk control timeout is implemented by jiffies. However
jiffies is not accurate enough thus "false timeout" may happen.

Use more accurate delay mechanism instead, i.e. ktime.

Link: https://lore.kernel.org/r/20200601104646.15436-2-stanley.chu@mediatek.com


Reviewed-by: Andy Teng <andy.teng@mediatek.com>
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Bug: 151050916
(cherry picked from commit c0a18ee0ce78d7957ec1a53be35b1b3beba80668)
Change-Id: I08b6204db64bcf52d9f32ebdb23c168a8b1e88af
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>