MIPS: PowerTV: Remove unused platform_die()

Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org>
Patchwork: http://patchwork.linux-mips.org/patch/800/


Reviewed-by: David VomLehn <dvomlehn@cisco.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>