of the MAC driver in order to attach miibus(4) on the first pass instead of
falling through to also calling it on the device_t of miibus(4). The latter
code flow was intended to attach the PHY drivers the same way regardless of
whether it's the first or a repeated pass, modulo the bus_generic_attach()
call in miibus_attach() which shouldn't be there. However, it turned out
that these variants cause miibus(4) to be attached twice under certain
conditions when using MAC drivers as modules.
Submitted by: yongari
MFC after: 3 days
d0fae855ef