net: if: Verify actual interface state instead of admin state on TX
net: if: Verify actual interface state instead of admin state on TX

When packet is passed to transmit at the net_if level, verify the
carrier state (NET_IF_LOWER_UP) instead of administrative state
(NET_IF_UP).

The administrative state is checked anyway at higher level (net_context)
so no need to verify it again. This will allow to still transmit control
packets for example when interface is in a dormant state.

Signed-off-by: Robert Lubos <9d28997c6894a2d0321a7bb399169af7ce99b64e@nordicsemi.no>

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