mm/migrate: Pass vm_fault pointer to migrate_misplaced_page()

migrate_misplaced_page() is only called during the page fault handling so
it's better to pass the pointer to the struct vm_fault instead of the vma.

This way during the speculative page fault path the saved vma->vm_flags
could be used.

Change-Id: I254a7c9d91dca9ee8a9afd5eccd6de9af5dc8bc0
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Patch-mainline: linux-mm @ Tue, 17 Apr 2018 16:33:19
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>