scsi: ufs: Introduce skipping manual flush for Write Booster

scsi: ufs: Introduce skipping manual flush for Write Booster

We have two knobs to control flush for write booster,
fWriteBoosterBufferFlushDuringHibernate and fWriteBoosterBufferFlushEn.

Some vendors use only fWriteBoosterBufferFlushDuringHibernate because this
can reportedly cover most scenarios. Also, there have been some reports
that flush by fWriteBoosterBufferFlushEn could lead to increased power
consumption thanks to unexpected internal operations. Consequently, we need
a way to enable or disable fWriteBoosterEn operations. Add quirk to bypass
manual flush.

Link: https://lore.kernel.org/r/ffdb0eda30515809f0ad9ee936b26917ee9b4593.1598319701.git.kwmad.kim@samsung.com
Reviewed-by: Avri Altman <avri.altman@wdc.com>
Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>