pci: use z specifier to format size_t

pci: use z specifier to format size_t

This addresses potential issues where size_t and off_t can vary
on some platforms.  For size_t the best way to format the value
is to use the z modifier to printf. For off_t need to cast to
long long to handle 64 bit offset on 32 bit platforms.

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