MIPS: PNX Removing dead CONFIG_PMCTWILED

CONFIG_PMCTWILED doesn't exist in Kconfig, therefore removing all
references for it from the source code.

Signed-off-by: Christoph Egger <siccegge@cs.fau.de>
To: linux-mips@linux-mips.org
To: linux-kernel@vger.kernel.org
Cc: vamos@i4.informatik.uni-erlangen.de
Acked-by: Shane McDonald <mcdonald.shane@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/1373/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>