MIPS: Octeon: remove orphan cvmx_fpa_setup_pool() declaration

All uses of cvmx_fpa_setup_pool() were removed by
commit a03822ea ("MIPS: OCTEON: Remove some unused files."),
so remove the orphan declaration, too.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>