FROMLIST: scsi: ufs: Add "Cold" regions timer

In order not to hang on to “cold” regions, we shall inactivate a
region that has no READ access for a predefined amount of time -
READ_TO_MS. For that purpose we shall monitor the active regions list,
polling it on every POLLING_INTERVAL_MS. On timeout expiry we shall add
the region to the "to-be-inactivated" list, unless it is clean and did
not exhaust its READ_TO_EXPIRIES - another parameter.

All this does not apply to pinned regions.

Bug: 183467926
Bug: 170940265
Bug: 183454255

Link: https://lore.kernel.org/lkml/20210607061401.58884-9-avri.altman@wdc.com/


Signed-off-by: Avri Altman <avri.altman@wdc.com>
Change-Id: I2d2efbbc612ccec6ef7036cc1e1d31bd8bfd4174