In some cases, platform thermal driver may report invalid trip points,
thermal core should not take any action for these trip points.

This fixed a regression that bogus trip point starts to screw up thermal
control on some Lenovo laptops, after
commit bb431ba2
Author: Zhang Rui <rui.zhang@intel.com>
Date:   Fri Oct 30 16:31:47 2015 +0800

    Thermal: initialize thermal zone device correctly

    After thermal zone device registered, as we have not read any
    temperature before, thus tz->temperature should not be 0,
    which actually means 0C, and thermal trend is not available.
    In this case, we need specially handling for the first
    thermal_zone_device_update().

    Both thermal core framework and step_wise governor is
    enhanced to handle this. And since the step_wise governor
    is the only one that uses trends, so it's the only thermal
    governor that needs to be updated.
Tested-by: NManuel Krause <manuelkrause@netscape.net>
Tested-by: Nszegad <szegadlo@poczta.onet.pl>
Tested-by: Nprash <prash.n.rao@gmail.com>
Tested-by: Namish <ammdispose-arch@yahoo.com>
Tested-by: NMatthias <morpheusxyz123@yahoo.de>
Reviewed-by: NJavi Merino <javi.merino@arm.com>
Signed-off-by: NZhang Rui <rui.zhang@intel.com>
Signed-off-by: NChen Yu <yu.c.chen@intel.com>

CC: <stable@vger.kernel.org> #3.18+
Link: https://bugzilla.redhat.com/show_bug.cgi?id=1317190
Link: https://bugzilla.kernel.org/show_bug.cgi?id=114551Signed-off-by: NZhang Rui <rui.zhang@intel.com>