nl80211: add ability to describe USB devices

nl80211: add ability to describe USB devices

Treat USB vendor and product IDs like PCI subsystem vendor and device IDs
respectively to allow describing USB devices as `0000 0000 $vid $pid` in
the hardware database.

As a side effect, this also skips potentially expensive MTD lookups on
embedded devices with plugged in USB radios.

With a 5.15 kernel, such MTD lookups even spam dmesg with:

    mtdblock: MTD device 'factory' is NAND, please consider using UBI block devices instead.

This fix speeds up iwinfo considerably on affected systems:

Before:
sys     0m 3.56s

After:
sys     0m 0.09s

Suggested-by: Andre Heider <a.heider@gmail.com>
Signed-off-by: Jo-Philipp Wich <jo@mein.io>