net: lwm2m: honor CONFIG_LWM2M_LOCAL_PORT when starting client
net: lwm2m: honor CONFIG_LWM2M_LOCAL_PORT when starting client

Currently, CONFIG_LWM2M_LOCAL_PORT is never used when setting up
the LwM2M client.  Let's set the port of the local address using
CONFIG_LWM2M_LOCAL_PORT, so that the client can bind to it.

NOTE: A setting of 0 will use a random port.

Signed-off-by: Michael Scott <17b9e1c64588c7fa6419b4d29dc1f4426279ba01@opensourcefoundries.com>

finikorg/zephyr,nashif/zephyr,Vudentz/zephyr,explora26/zephyr,Vudentz/zephyr,mbolivar/zephyr,nashif/zephyr,punitvara/zephyr,finikorg/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,mbolivar/zephyr,punitvara/zephyr,punitvara/zephyr,zephyriot/zephyr,mbolivar/zephyr,explora26/zephyr,ldts/zephyr,Vudentz/zephyr,zephyriot/zephyr,kraj/zephyr,ldts/zephyr,finikorg/zephyr,nashif/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,ldts/zephyr,mbolivar/zephyr,mbolivar/zephyr,Vudentz/zephyr,kraj/zephyr,nashif/zephyr,explora26/zephyr,kraj/zephyr,zephyriot/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,GiulianoFranchetto/zephyr,kraj/zephyr,ldts/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,nashif/zephyr,ldts/zephyr,galak/zephyr,zephyriot/zephyr,zephyriot/zephyr,zephyrproject-rtos/zephyr,GiulianoFranchetto/zephyr,explora26/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,GiulianoFranchetto/zephyr