mm: remove obsolete pgdat_is_empty()

There's no caller.  Remove it.

Link: https://lkml.kernel.org/r/20220916072257.9639-8-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mmzone.h

@@ -1241,11 +1241,6 @@ static inline unsigned long pgdat_end_pfn(pg_data_t *pgdat)
 	return pgdat->node_start_pfn + pgdat->node_spanned_pages;
 }
 
-static inline bool pgdat_is_empty(pg_data_t *pgdat)
-{
-	return !pgdat->node_start_pfn && !pgdat->node_spanned_pages;
-}
-
 #include <linux/memory_hotplug.h>
 
 void build_all_zonelists(pg_data_t *pgdat);