net: ethernet: Clean an obscure ref/unref logic in ethernet_send()
net: ethernet: Clean an obscure ref/unref logic in ethernet_send()

Do not extra ref and then obscurely unref the packet inside
the statistics update function.

Actually, this extra ref/unref isn't needed here at all.

The packet is unreferenced only on a successful send, statistics
updating can be done before the unref in a clean and understandable way.

Signed-off-by: Oleg Zhurakivskyy <cdb82bfa180f8df716a77d2c2557196a597a233c@intel.com>

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