mm/hotplug: kill is_dev_zone() usage in __remove_pages()

The zone type check was a leftover from the cleanup that plumbed altmap
through the memory hotplug path, i.e.  commit da02451 "mm: pass the
vmem_altmap to arch_remove_memory and __remove_pages".

Link: http://lkml.kernel.org/r/156092352642.979959.6664333788149363039.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <[email protected]>
Reviewed-by: David Hildenbrand <[email protected]>
Reviewed-by: Oscar Salvador <[email protected]>
Tested-by: Aneesh Kumar K.V <[email protected]>	[ppc64]
Cc: Michal Hocko <[email protected]>
Cc: Logan Gunthorpe <[email protected]>
Cc: Pavel Tatashin <[email protected]>
Cc: Jane Chu <[email protected]>
Cc: Jeff Moyer <[email protected]>
Cc: Jérôme Glisse <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Toshi Kani <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Wei Yang <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/memory_hotplug.c

@@ -535,9 +535,7 @@ void __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
 	unsigned long map_offset = 0;
 	int sections_to_remove;
 
-	/* In the ZONE_DEVICE case device driver owns the memory region */
-	if (is_dev_zone(zone))
-		map_offset = vmem_altmap_offset(altmap);
+	map_offset = vmem_altmap_offset(altmap);
 
 	clear_zone_contiguous(zone);