net/lib: 15.4 interface is set UP after channel is configured
net/lib: 15.4 interface is set UP after channel is configured

Once it has - at least - set up the channel, it can request the iface to
be put up.

Signed-off-by: Tomasz Bursztyka <ba81a3a719836727e6857ae83462b9f52ec41006@linux.intel.com>

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