ppc/pnv: Move the PNOR LPC address into struct PnvPnor

ppc/pnv: Move the PNOR LPC address into struct PnvPnor

Rather than use the hardcoded define throughout the tree for the
PNOR LPC address, keep it within the PnvPnor object.

This should solve a dead code issue in the BMC HIOMAP checks where
Coverity (correctly) reported that the sanity checks are dead code.
We would like to keep the sanity checks without turning them into a
compile time assert in case we would like to make them configurable
in future.

Fixes: 4c84a0a4a6e5 ("ppc/pnv: Add a PNOR address and size sanity checks")
Resolves: Coverity CID 1593723
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>