bus/pci: align next mapping address on page boundary

Currently, the next address picked by PCI mapping infrastructure
may be page-unaligned due to BAR length being smaller than page size.
This leads to a situation where the requested map address is invalid,
resulting in mmap() call returning an arbitrary address,
which will later interfere with device BAR mapping in secondary processes.

Fix it by always aligning the next requested address on page boundary.

Fixes: c752998b5e2e ("pci: introduce library and driver")
Cc: stable@dpdk.org
Signed-off-by: Xiaofeng Deng <dengxiaofeng@huawei.com>
Signed-off-by: Wangyu (Eric) <seven.wangyu@huawei.com>
Acked-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
Acked-by: Min Hu (Connor) <humin29@huawei.com>
Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>
Acked-by: Gavin Hu <gavin.hu@arm.com>