physRpn_to_absRpn is a no-op on non-iSeries platforms, remove the two
redundant calls.

There's only one caller on iSeries so fold the logic in there so we can get
rid of it completely.
Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>