ARM: dts: Remove thermistors on all revs of snow

It appears that thermistors were not stuffed on at least some (perhaps
all?) snow-rev4 machines.  It turns out that thermistors were not
particularly useful for thermal throttling on snow since the CPU
temperature is very highly correlated with the thermistor temperature
due to excellent heat spreading on snow.  Rather than forking the snow
dts yet another time between rev3 and rev4, just remove thermistors
from all revs of snow.

BUG=chromium:343569
TEST=On rev3, rev4, and rev5, /var/log/messages after boot shows:
  "Max CPU Freq set to 1700000 (Celsius: 41 )"

Change-Id: Ibff580c3ba55f41d82f231e95eb3c3eb23542ba9
Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/186357
Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Reviewed-by: Olof Johansson <olofj@chromium.org>
Reviewed-by: Ilja Friedel <ihf@chromium.org>
Reviewed-by: Jaehoon Kim <jh228.kim@samsung.com>
(cherry picked from commit 2413925bc296ba496ef62a0e8f1ab697f1f68111)
Reviewed-on: https://chromium-review.googlesource.com/186612
Reviewed-by: Matthew Yuan <matthewyuan@chromium.org>
Tested-by: Matthew Yuan <matthewyuan@chromium.org>