powerpc/powernv/sriov: Remove vfs_expanded

Previously iov->vfs_expanded was used for two purposes.

1) To work out how much we need to multiple the per-VF BAR size to figure
   out the total space required for the IOV BAR.

2) To indicate that IOV is not usable with this device (vfs_expanded == 0).

We don't really need the field for either since the multiple in 1) is
always the number PEs supported by the PHB. Similarly, we don't really need
it in 2) either since the IOV data field will be NULL if we can't use IOV
with the device.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200722065715.1432738-16-oohall@gmail.com