powerpc/eeh: Delete eeh_pe->config_addr

The eeh_pe->config_addr field was supposed to be removed in
commit 35d64734

 ("powerpc/eeh: Clean up PE addressing") which made it
largely unused. Finish the job.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201007040903.819081-1-oohall@gmail.com