mm/memory_hotplug.c: remove unused local zone_type from __remove_zone()

__remove_zone() sets up up zone_type, but never uses it for anything.
This does not cause a warning, due to the (necessary) use of
-Wno-unused-but-set-variable.  However, it's noise, so just delete it.

Link: http://lkml.kernel.org/r/20170624043421.24465-2-jhubbard@nvidia.com
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory_hotplug.c

@@ -580,11 +580,8 @@ static void __remove_zone(struct zone *zone, unsigned long start_pfn)
 {
 	struct pglist_data *pgdat = zone->zone_pgdat;
 	int nr_pages = PAGES_PER_SECTION;
-	int zone_type;
 	unsigned long flags;
 
-	zone_type = zone - pgdat->node_zones;
-
 	pgdat_resize_lock(zone->zone_pgdat, &flags);
 	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
 	shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages);