Especially for "virtual" devices (e.g. wdog0 or mmc2), it is often
useful to know the corresponding hardware device.

Instead of always having to search through plain devinfo, just
include this information in the output when running
`devinfo device`.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>