iot2050: Add watchdog start to bootcmd

Allows run-time control over watchdog auto-start and the timeout via
setting the environment variable watchdog_timeout_ms. A value of zero
means "do not start". Use CONFIG_WATCHDOG_TIMEOUT_MSECS as initial value
and this to zero by default. Users can then enable the watchdog once the
use and OS which picks it up during boot.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
diff --git a/configs/iot2050_pg1_defconfig b/configs/iot2050_pg1_defconfig
index 57a2a6d..3075021 100644
--- a/configs/iot2050_pg1_defconfig
+++ b/configs/iot2050_pg1_defconfig
@@ -32,6 +32,7 @@
 CONFIG_BOOTSTAGE=y
 CONFIG_SHOW_BOOT_PROGRESS=y
 CONFIG_SPL_SHOW_BOOT_PROGRESS=y
+CONFIG_BOOTCOMMAND="run start_watchdog; run distro_bootcmd"
 CONFIG_CONSOLE_MUX=y
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_SPL_MAX_SIZE=0x58000
@@ -140,6 +141,7 @@
 CONFIG_USB_KEYBOARD=y
 # CONFIG_WATCHDOG is not set
 # CONFIG_WATCHDOG_AUTOSTART is not set
+CONFIG_WATCHDOG_TIMEOUT_MSECS=0
 CONFIG_WDT=y
 CONFIG_WDT_K3_RTI=y
 CONFIG_WDT_K3_RTI_LOAD_FW=y