iommu/amd: Move iommu_init_pci() to .init section

commit 24d2c521 upstream.

The function is only called from another __init function, so
it should be moved to .init too.

Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>