powerpc/powernv/pci: Remove obsoleted declaration for pnv_pci_init_ioda_hub

The pnv_pci_init_ioda_hub() have been removed since
commit 5ac129cd ("powerpc/powernv/pci: Remove ioda1 support"),
and now it is useless, so remove it.

Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20240822130043.783756-1-cuigaosheng1@huawei.com