spapr_numa.c: fixes in spapr_numa_FORM2_write_rtas_tables()

spapr_numa.c: fixes in spapr_numa_FORM2_write_rtas_tables()

This patch has a handful of modifications for the recent added
FORM2 support:

- to not allocate more than the necessary size in 'distance_table'.
At this moment the array is oversized due to allocating uint32_t for
all elements, when most of them fits in an uint8_t. Fix it by
changing the array to uint8_t and allocating the exact size;

- use stl_be_p() to store the uint32_t at the start of 'distance_table';

- use sizeof(uint32_t) to skip the uint32_t length when populating the
distances;

- use the NUMA_DISTANCE_MIN macro from sysemu/numa.h to avoid hardcoding
the local distance value.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20210922122852.130054-2-danielhb413@gmail.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>