MFC: r284447, r284552

Merge from NetBSD:
o rev. 1.10: Nuke trailing whitespace.
o rev. 1.15: Fix typo in comment.
o rev. 1.16: Add the following registers from IEEE 802.3-2009 Clause 22:

• PSE control register (0x0b)
• PSE status register (0x0c)
• MMD access control register (0x0d)
• MMD access address data register (0x0e)

o rev. 1.17 (comments only): The bit location of link ability is different

between 1000Base-X and others (see Annex 28B.2 and 28D).

o rev. 1.18: Nuke dupe word.

Obtained from: NetBSD
Sponsored by: genua mbh