usb: netusb: Rework netusb media connect/disconnect
usb: netusb: Rework netusb media connect/disconnect

Consider media connected when interface is selected by the host and
disconnected on device diconnection.

Signed-off-by: Loic Poulain <7dbc6498a90ff1ada42fc224430b4f763baa5c5c@linaro.org>

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