net: dhcp: fix bounds check in timeout
net: dhcp: fix bounds check in timeout

The flag value UINT32_MAX is returned from manage_timers() when a send
operation did not succeed.  This indicates that the timeout should not
be rescheduled, but because it will never replace the starting update
value UINT32_MAX-1 the check will never pass, and in cases where it
should work will be submitted to run at UINT32_MAX-1 seconds.

Fix the upper bound.

Signed-off-by: Peter Bigot <a4112a160b558d5427af084318038e19a95979ee@nordicsemi.no>

Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,nashif/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr