MIPS: Octeon: Remove redundant declaration of octeon_reserve32_memory

octeon_reserve32_memory is defined In Octeon's setup.c, so remove the
redundant extern declaration of this variable.

Signed-off-by: Yang Shi <yang.shi@windriver.com>
To: f.fainelli@gmail.com
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/1022/
Acked-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>