FIX: Intel e1000 emulation
FIX: Intel e1000 emulation

This supersedes commit b8260e2453821d9124576e55ecc0bcf1a934aa85. This
actually is contains the code implements e1000 for the bhyve guest.

Intel e1000 emulation is now supported on older versioned FreeBSD
hosts. Now a better check is ran to check if on a supported version.

Originally Intel e1000 emulation was committed on 12-CURRENT at r302504
MFCed to 11-STABLE at r304424
MFCed to 10-STABLE at r304425

chyves/chyves