Fix some issues with Ethernet status on FreeBSD

[bsdjhb]

Sorry I don't have a pull request ready, but I committed a patch to FreeBSD's ports tree with various fixes for the Ethernet status on FreeBSD. Here are the details from the commit message and a reference to the commit which includes the patch file:

https://svnweb.freebsd.org/ports?view=revision&revision=393973

Fix some nits with displaying Ethernet media status exposed by the recent extended Ethernet media states:

• Don't apply IFM_SUBTYPE to the raw subtype in the description table. IFM_SUBTYPE() requires a fully populated word and was truncating values in the table when comparing resulting in false matches (notably "10GBase-KX4" for the no media case).
• Explicitly check for IFM_ETHER.
• Use SIOCGIFXMEDIA when present to obtain extended media states.
• Explicitly handle "no carrier".

[stapelberg]

Can you just send this as a pull request please? That makes merging so much easier.

[bsdjhb]

Done as request #58

[stapelberg]

Thanks!