QoS: Use Intermediate Functional Block

QoS: Use Intermediate Functional Block

This is an alternative implementation to the Intermediate Queuing
Device (IMQ) which is an out-of-tree kernel patch and has been
criticised for being slow, especially with mutliple processors.

IFB is part of the mainline kernel and a lot less code.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Signed-off-by: Daniel Weismüller <daniel.weismueller@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>