The igb(4) driver supports 82580, i350, i354, i210 and i211 chipsets too,
document them.

PR:		192301
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@273197 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f