mm/memory: remove unnecessary pte_devmap case in copy_one_pte()

Since commit 25b2995a ("mm: remove MEMORY_DEVICE_PUBLIC support"),
the assignment to 'page' for pte_devmap case has been unnecessary.
Let's remove it.

[willy@infradead.org: changelog]
Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Link: http://lkml.kernel.org/r/1587349685-31712-1-git-send-email-qiwuchen55@gmail.comSigned-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -802,8 +802,6 @@ copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
 		get_page(page);
 		page_dup_rmap(page, false);
 		rss[mm_counter(page)]++;
-	} else if (pte_devmap(pte)) {
-		page = pte_page(pte);
 	}
 
 out_set_pte: