Now that we have HZ=1000 there is much less of a need for decr_overclock.
Remove it.

Leave spread_lpevents but move it into iSeries_setup.c.  We should look at
making event spreading the default some day.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Acked-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>