pseries: Remove redundant calls to spapr_machine_initfn()

pseries: Remove redundant calls to spapr_machine_initfn()

The instance_init() functions for several of the pseries-x.y versioned
machine types explicitly call spapr_machine_initfn().  But that's the
instance_init function for the common parent of all those machine types,
so will already have been called beforehand by the QOM infrastructure.

Remove the redundant calls.

Signed-off-by: David Gibson <[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Reviewed-by: Alexey Kardashevskiy <[email protected]>