apm821xx: use the real default HZ value from upstream

apm821xx: use the real default HZ value from upstream

With the "real HZ" debate out of the way, let's actually
use the apm821xx's default upstream config file at
arch/powerpc/configs/44x/bluestone_defconfig. From what
I can tell, it sets NO_HZ (well, this platform was for
NAS, so this is a bit unexpected) and remove any specific
HZ_$VALUE symbol.

Sadly, Daniel Engberg didn't run any before/after netperf
tests, because it would have been such a slam dunk across
the boards. In case of the apm821xx the tcp tx/rx
performance improved ~14% (from 600Mbps to 700Mps).
This now causes the emac to drop frames too, so let's see
if this is causes more problems or not.

This patch includes a refresh of the configuration too.

Signed-off-by: Christian Lamparter <chunkeey@gmail.com>