spapr, spapr_numa: move lookup-arrays handling to spapr_numa.c

spapr, spapr_numa: move lookup-arrays handling to spapr_numa.c

In a similar fashion as the previous patch, let's move the
handling of ibm,associativity-lookup-arrays from spapr.c to
spapr_numa.c. A spapr_numa_write_assoc_lookup_arrays() helper was
created, and spapr_dt_dynamic_reconfiguration_memory() can now
use it to advertise the lookup-arrays.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20200903220639.563090-4-danielhb413@gmail.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>