util: pci: define cleanup function using VIR_DEFINE_AUTOPTR_FUNC
    
    Using the new VIR_DEFINE_AUTOPTR_FUNC macro defined in
    src/util/viralloc.h, define a new wrapper around an existing
    cleanup function which will be called when a variable declared
    with VIR_AUTOPTR macro goes out of scope. Also, drop the redundant
    viralloc.h include, since that has moved from the source module into
    the header.
    
    When variables of types virPCIDevicePtr, virPCIDeviceAddressPtr
    and virPCIEDeviceInfoPtr are declared using VIR_AUTOPTR, the functions
    virPCIDeviceFree, virPCIDeviceAddressFree and virPCIEDeviceInfoFree,
    respectively, will be run automatically on them when they go out of scope.
    
    Signed-off-by: Sukrit Bhatnagar <skrtbhtngr@gmail.com>
    Reviewed-by: Erik Skultety <eskultet@redhat.com>