net: context: connect: Make sure local end is bound before connecting
net: context: connect: Make sure local end is bound before connecting

Introduce net_context_bind_default() to ensure that local address is
set for context if not yet (via explict bind() call). This fixes
dereferences of NULL pointer to local address which was exposed when
MMU was enabled for qemu_x86.

Signed-off-by: Paul Sokolovsky <35cb557f011771c94f127d6fef99f804b62203f5@linaro.org>

aceofall/zephyr-iotos,fbsder/zephyr,mbolivar/zephyr,fbsder/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,fbsder/zephyr,ldts/zephyr,GiulianoFranchetto/zephyr,punitvara/zephyr,explora26/zephyr,zephyrproject-rtos/zephyr,explora26/zephyr,rsalveti/zephyr,runchip/zephyr-cc3220,ldts/zephyr,aceofall/zephyr-iotos,Vudentz/zephyr,mbolivar/zephyr,Vudentz/zephyr,zephyriot/zephyr,explora26/zephyr,mbolivar/zephyr,explora26/zephyr,mbolivar/zephyr,galak/zephyr,kraj/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,zephyriot/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,punitvara/zephyr,Vudentz/zephyr,rsalveti/zephyr,ldts/zephyr,zephyriot/zephyr,kraj/zephyr,punitvara/zephyr,nashif/zephyr,aceofall/zephyr-iotos,mbolivar/zephyr,zephyriot/zephyr,kraj/zephyr,explora26/zephyr,ldts/zephyr,nashif/zephyr,kraj/zephyr,runchip/zephyr-cc3220,punitvara/zephyr,rsalveti/zephyr,zephyriot/zephyr,galak/zephyr,nashif/zephyr,runchip/zephyr-cc3220,ldts/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,GiulianoFranchetto/zephyr,aceofall/zephyr-iotos,GiulianoFranchetto/zephyr,fbsder/zephyr,kraj/zephyr,GiulianoFranchetto/zephyr,Vudentz/zephyr,galak/zephyr,GiulianoFranchetto/zephyr,galak/zephyr,runchip/zephyr-cc3220,finikorg/zephyr,aceofall/zephyr-iotos,rsalveti/zephyr,nashif/zephyr,rsalveti/zephyr,fbsder/zephyr,punitvara/zephyr,runchip/zephyr-cc3220,Vudentz/zephyr,nashif/zephyr