maybe_download_initmd() configured net0, the first interface the firmware
lists, which need not be the one the loader was booted from. On a machine
with several interfaces net0 may have no link or no DHCP server, and the
loader then waits for a DHCP reply there, printing nothing, until the
firmware's boot watchdog resets the machine. If net0 does answer, later
opens of the boot interface reuse the socket configured on the wrong one.
Find the interface whose MAC address matches the device path of the loaded
image and configure that one instead.
Reported by: Patrick Sanderson
Fixes: d48e9bff8c02 ("loader.efi: fetch initmd specified by DHCP")
Sponsored by: Rubicon Communications, LLC ("Netgate")