yocto/zephyr-kernel: Add downstream patches for the VLAN handling

Add two downstream patches for the VLAN handling, one is an enhancement
for the network config library to add support for the VLAN configuration,
the other is a fix for a bug on the computation of the Ethernet header
frame size.

Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>