fwget: update pci_network_mediatek for mt7996

Add support for another chipset and fix mt7915 to not match on
all IDs.

fwget: add support for various WiFi NICs

Add support for Realtek, QCA, and Mediatek WiFi NIC cards.
We group the matching entries by driver in sub-functions in order
to semi-automatically create the lists for now.

Reviewed by: manu
Differential Revision: https://reviews.freebsd.org/D40073