powerpc/pseries/ibmebus: Remove legacy suspend/resume support

There are no ibmebus driver that make use of legacy suspend/resume. This
patch removes the support for it from ibmebus framework, new ibmebus
driver (as unlikely as they are) wanting to use suspend/resume should
use dev_pm_ops.

Since there aren't any special bus specific things to do during
suspend/resume and since the PM core will automatically fallback
directly to using the device's PM ops if no bus PM ops are specified
there is no need to have any special ibmebus PM ops at all.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>