osd/ReplicatedPG: fix promotion recency logic

osd/ReplicatedPG: fix promotion recency logic

Recency is defined as how many of the last N hitsets an object
must appear in in order to be promoted.  The previous logic did
nothing of the sort... it checked for the object in any one of
the last N hitsets, which led to way to many promotions and killed
any chance of the cache performing properly.

While we are here, we can simplify the code to drop the max_in_*
fields (no longer necessary).

Note that we may still want a notion of 'temperature' that does
tolerate the object missing in one of the recent hitsets.. but
that would be different than recency, and should probably be
modeled after the eviction temperature model.

Backport: infernalis, hammer
Reported-by: Nick Fisk <nick@fisk.me.uk>
Signed-off-by: Sage Weil <sage@redhat.com>
(cherry picked from commit 180c8743addc5ae2f1db9c58cd2996ca6e7ac18b)

Conflicts:
	src/osd/ReplicatedPG.cc
                    code section was moved to ReplicatedPG::maybe_promote
                    in master.
Signed-off-by: Robert LeBlanc <robert.leblanc@endurance.com>