Handling slow interfaces

[caguiclajmg]

I'm currently testing the ArchLinuxARM aarch64 image on an RPi3 and noticed that the hook fails when faced with interfaces that take a little bit of time to come up.

Basically what I see in the boot messages are:

ipconfig: no devices to configure
... some odd seconds pass
smsc95xx eth0: register 'smsc95xx'

I've tried setting netconf_timeout but it still fails with the familiar ipconfig: no devices to configure message error message probably because that timeout parameter is for something else (probably DHCP or something).

Adding a delay (sleep 10) at the start of the hook works and could probably be modified to read the parameter from the kernel command line.