power_status: Fix pylint warnings/errors

Errors:
    * Hook script "./utils/run_pylint.py" failed with code 4:
      Using config file /usr/local/google/home/campello/chromiumos/src/third_party/autotest/files/utils/pylintrc
      ************* Module power_status
      W:147,16: Specify string format arguments as logging function parameters (logging-not-lazy)
      W:470,12: Specify string format arguments as logging function parameters (logging-not-lazy)
      W:945,20: Specify string format arguments as logging function parameters (logging-not-lazy)

      ------------------------------------------------------------------
      Your code has been rated at 9.98/10 (previous run: 9.98/10, +0.00)

BUG=None
TEST=None

Change-Id: Ie9e47309ec1164e25aaa39212606985c97b47c51
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1947583
Reviewed-by: Derek Beckett <dbeckett@chromium.org>
Tested-by: Daniel Campello <campello@chromium.org>
Commit-Queue: Daniel Campello <campello@chromium.org>
diff --git a/client/cros/power/power_status.py b/client/cros/power/power_status.py
index 3591a79..9dbfddc 100644
--- a/client/cros/power/power_status.py
+++ b/client/cros/power/power_status.py
@@ -143,9 +143,8 @@
             if field.find('trip_point_') != -1 and field.find('_temp') != -1 \
                     and self.temp > self.read_val(field, int):
                 self.num_points_tripped += 1
-                logging.info('Temperature trip point #' + \
-                            field[len('trip_point_'):field.rfind('_temp')] + \
-                            ' tripped.')
+                logging.info('Temperature trip point #%s tripped.', \
+                            field[len('trip_point_'):field.rfind('_temp')])
 
 
 class ThermalStatHwmon(DevStat):
@@ -466,7 +465,7 @@
 
         temp_str = self.thermal.get_temps()
         if temp_str:
-            logging.info('Temperature reading: ' + temp_str)
+            logging.info('Temperature reading: %s', temp_str)
         else:
             logging.error('Could not read temperature, skipping.')
 
@@ -879,8 +878,8 @@
                     # Kernel race condition that can happen while a new C-state
                     # gets added (e.g. AC->battery). Don't know the 'name' of
                     # the state yet, but its 'time' would be 0 anyway.
-                    logging.warning('Read name: <null>, time: %d from %s'
-                        % (usecs, state) + '... skipping.')
+                    logging.warning('Read name: <null>, time: %d from %s...'
+                                    'skipping.', usecs, state)
                     continue
 
                 cpuidle_stats[name] += usecs