kernel: Do not start pinging the watchdog too early

Of course we want to wait for the full bootup of our system and only
*then* start pinging the watchdog. That's been the plan since the very
beginning, otherwise there's very little point in doing our extra dance.

I wonder how come I missed this option :). Perhaps it's because this got
"only" merged in v4.13...

Change-Id: Ia005e5d96c5f730996f2373a684a74baecff8b46
Bug: https://tree.taiga.io/project/jktjkt-czechlight/issue/711
diff --git a/board/czechlight/common/linux.fragment b/board/czechlight/common/linux.fragment
index cf6727f..b5f86f2 100644
--- a/board/czechlight/common/linux.fragment
+++ b/board/czechlight/common/linux.fragment
@@ -52,6 +52,7 @@
 CONFIG_WATCHDOG_NOWAYOUT=y
 CONFIG_WATCHDOG_SYSFS=y
 CONFIG_WATCHDOG_PRETIMEOUT_GOV=y
+CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED=n
 
 # protecting /etc
 CONFIG_OVERLAY_FS=y