x86/NUMA: improve memnode_shift calculation for multi node system

x86/NUMA: improve memnode_shift calculation for multi node system

SRAT may describe individual nodes using multiple ranges. When they're
adjacent (with or without a gap in between), only the start of the first
such range actually needs accounting for. Furthermore the very first
range doesn't need considering of its start address at all, as it's fine
to associate all lower addresses (with no memory) with that same node.
For this to work, the array of ranges needs to be sorted by address -
adjust logic accordingly in acpi_numa_memory_affinity_init().

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>