Fix bhyve PCIe capability emulation

PCIe devices starting with version 1.1 must set the Role-Based Error
Reporting bit.

And while we're in the neighborhood, generalize the code assigning the
device type.

Reviewed by: imp, araujo, rgrimes
Approved by: imp (mentor)
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D19580