powerpc/83xx: fix RGMII AC values workaround for km83xx

Fix RGMII workaround code in km83xx.c for MPC8360E and MPC8358E that it
correctly identifes all affected SoC chip models and applies the
workarounds appropriate for 2.0 and 2.1 revisions as per Freescale
MPC8360ECE Errata document Rev.5(9/2011) item QE_ENET10.

Signed-off-by: Christian Herzig <christian.herzig@keymile.com>
Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
cc: Heiko Schocher <hs@denx.de>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>