powerpc/ps3: make two symbols static

This addresses the following sparse warning:

arch/powerpc/platforms/ps3/spu.c:451:33: warning: symbol
'spu_management_ps3_ops' was not declared. Should it be static?
arch/powerpc/platforms/ps3/spu.c:592:28: warning: symbol
'spu_priv1_ps3_ops' was not declared. Should it be static?

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200911020121.1464585-1-yanaijie@huawei.com