ppc, 8321: cleanup tuxa1, tuda1 and suvd3 support

For the kmsupx5 a new header file was introduced km8321-common.h.
Now the common stuff from tuxa1, tuda1 and suvd3 was removed and
the new header file included.

The defines CONFIG_SYS_PIGGY_BASE and CONFIG_SYS_PIGGY_SIZE are
confusing. Because they actually describe the KMBEC FPGA values.
The KMBEC FPGA can be PRIO on kmeter1 or upio on mgcoge. Therefore
all the defines were renamed.

remove unneeded variable CONFIG_KM_DEF_NETDEV, as it is
already declared in keymile-common.h

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Signed-off-by: Heiko Schocher <hs@denx.de>
Acked-by: Kim Phillips <kim.phillips@freescale.com>
cc: Kim Phillips <kim.phillips@freescale.com>
cc: Wolfgang Denk <wd@denx.de>
cc: Valentin Longchamp <valentin.longchamp@keymile.com>