kernel: Change timer tick to 1000Hz

kernel: Change timer tick to 1000Hz

This change is required to make the system respond faster to any
realtime events (sending or receiving data packets).

It will wake up at least one core 1000 times a second which will result
in finer timer granularity and make scheduling smoother. HTB for
example sends large packet bursts on each timer even to keep up data
rates which is not helpful for most applications.

The change might increase resource consumption and overhead slightly on
some systems, but since we are running in an idle-dyntick configuration,
we should not keep awake any cores that have not been awake before.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
Acked-by: Peter Müller <peter.mueller@ipfire.org>
Signed-off-by: Arne Fitzenreiter <arne_f@ipfire.org>