Update kernel

Change-Id: Iaf5cffc1c9eb9eaa2cbc368ca8eaec0ea2e74882
diff --git a/board/czechlight/clearfog/overlay/usr/lib/systemd/system/max31780-fans.service b/board/czechlight/clearfog/overlay/usr/lib/systemd/system/max31780-fans.service
index a7b1d56..f9a9576 100644
--- a/board/czechlight/clearfog/overlay/usr/lib/systemd/system/max31780-fans.service
+++ b/board/czechlight/clearfog/overlay/usr/lib/systemd/system/max31780-fans.service
@@ -10,4 +10,6 @@
 [Service]
 Type=oneshot
 RemainAfterExit=yes
-ExecStart=/bin/bash -c 'for FAN in /sys/bus/i2c/devices/1-0020/hwmon/hwmon*/fan{1,2,3,4}_enable; do echo 1 > "$FAN"; done'
+# The driver only supports enabling RPM input when setting RPM mode. It also does not reset the RPM input when switching back to PWM mode.
+# So, we first enable RPM mode (2), this sets the TACH_ENABLE bit and then set PWM mode, because RPM mode doesn't work anyway.
+ExecStart=/bin/bash -c 'for FAN in /sys/bus/i2c/devices/1-0020/hwmon/hwmon*/pwm{1,2,3,4}_enable; do echo 2 > "$FAN"; echo 1 > "$FAN"; done'