Add support for 2.5G, 5G, 25G, and 50G based Ethernet

[erhauser]

The current implementation lacks support for 2.5G, 5G, 25G and 50G Ethernet.
Because of this lldpcli show interfaces details shows unknown for MAU oper type on such interfaces.

To solve this, I have extended lldpd in the follwing way:

1. Added new mautypes in src/lib/atoms/port.c and src/lldp-const.h according to IANA-MAU-MIB.
2. Added new cases in src/daemon/interfaces-linux.c to identify the new Ethernet speeds.

For 25G, I suggest to use 25GBASE-T for regular RJ45, 25GBASE-LR for fibre, and 25GBASE-CR for DAC-cables.
For 50G there is no RJ45-based standard available (yet), therefore we only have 50GBASE-LR for fibre and 50GBASE-CR for DAC-cable.
Both, 2.5G and 5G, build on RJ45 cabling, therefore 2.5GBASE-T and 5GBASE-T, respectively.

[vincentbernat]

This looks good. Thanks!

[erhauser]

Thanks!
The second commit 87d7bd7 adds support for the available RJ45 10GBASE-T and updates the older 100GBASE-CR10 ("phase-out" cf. Wikipedia 100G Ethernet) to the newer ("current") 100GBASE-CR4 standard.

[vincentbernat]

Looks like the 10G change also needs to update some of the tests.

[vincentbernat]

Thanks!