UPSTREAM: scsi: ufs-mediatek: Introduce event_notify implementation

Introduce event_notify implementation on MediaTek UFS platform. A
vendor-specific tracepoint is added that can be used for debugging
purposes.

Bug: 188004633
Change-Id: Ie3d1f3f3651b9e81a1d28f287459746b93381969
(cherry picked from commit ca1bb061)
Link: https://lore.kernel.org/r/20201205115901.26815-5-stanley.chu@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>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>