BACKPORT: FROMGIT: mm: Pass 'address' to map to do_set_pte() and drop FAULT_FLAG_PREFAULT

Rather than modifying the 'address' field of the 'struct vm_fault'
passed to do_set_pte(), leave that to identify the real faulting address
and pass in the virtual address to be mapped by the new pte as a
separate argument.

This makes FAULT_FLAG_PREFAULT redundant, as a prefault entry can be
identified simply by comparing the new address parameter with the
faulting address, so remove the redundant flag at the same time.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Will Deacon <will@kernel.org>
Change-Id: I495c06047bac0f4e2241bc47a18b8ee8f97e4af8
Bug: 171278850
(cherry picked from commit 9d3af4b4
https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=for-next/faultaround

)
[vinmenon: changes for speculative page fault]
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>