Remove REDWOOD_[456] config options and conditional code

The config options for REDWOOD_[456] were commented out in the powerpc
Kconfig. The ifdefs referencing this options therefore are dead and all
references to this can be removed (Also dependencies in other KConfig
files).

Signed-off-by: Christian Dietrich <qy03fugy@stud.informatik.uni-erlangen.de>
Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>