if_muge: Add LAN78xx family USB ids but attach only to LAN7800

This driver was developed for the LAN7800 and the register-compatible
LAN7515 and has only been tested on those devices. Adding support for
other members of the family should be straightforward, once we have
devices to test.

With this change the driver will probe but fail to attach due to the
Chip ID check, but will leave a hint leading to the driver that needs
work.

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D15537