FROMLIST: scsi: ufs: Add region's reads counter

In host control mode, reads are the major source of activation trials.
Keep track of those reads counters, for both active as well inactive
regions.

We reset the read counter upon write - we are only interested in "clean"
reads.

Keep those counters normalized, as we are using those reads as a
comparative score, to make various decisions.
If during consecutive normalizations an active region has exhaust its
reads - inactivate it.

while at it, protect the {active,inactive}_count stats by adding them
into the applicable handler.

Bug: 183467926
Bug: 170940265
Bug: 183454255

Link: https://lore.kernel.org/lkml/20210607061401.58884-5-avri.altman@wdc.com/


Signed-off-by: Avri Altman <avri.altman@wdc.com>
Change-Id: I0541c39e3dd7656ca1816cac3599ab73eb8697a8