pci: increase domain storage to 32 bits

pci: increase domain storage to 32 bits

In some environments, the PCI domain can be larger than 16 bits.
For example, a PCI device passed through in Azure gets a synthetic domain
id  which is internally generated based on GUID. The PCI standard does
not restrict domain to be 16 bits.

This change breaks ABI for API's that expose PCI address structure.

The printf format for PCI remains unchanged, so that on most
systems (with only 16 bit domain) the output format is unchanged
and is 4 characters wide.  For example: 0000:00:01.0
Only on sysetms with higher bits will the domain take up more
space; example: 12000:00:01.0

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>