hugetlb: simplify migrate_huge_page()

hugetlb: simplify migrate_huge_page()

Since we migrate only one hugepage, don't use linked list for passing the
page around.  Directly pass the page that need to be migrated as argument.
This also removes the usage of page->lru in the migrate path.

Signed-off-by: Aneesh Kumar K.V <[email protected]>
Reviewed-by: KAMEZAWA Hiroyuki <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Hillf Danton <[email protected]>
Reviewed-by: Michal Hocko <[email protected]>
Cc: KOSAKI Motohiro <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>