ANDROID: GKI: mm: add struct vm_fault fields for SPECULATIVE_PAGE_FAULTS

Two new fields in the struct vm_fault can't easily be excluded using
CONFIG_SPECULATIVE_PAGE_FAULTS. Add them as padding to reduce the
ABI diff between vendors which use SPECULATIVE_PAGE_FAULTS and ACK. This
allows vendors to pick the SPECULATIVE_PAGE_FAULTS feature and still be
ABI compatible with ACK.

Bug: 153715905
Test: build
Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
(cherry picked from commit 47e3eb155848872a13ab6ef73a4d0eecac36ce66)
[surenb: kept only struct vm_fault changes and dropped the rest]
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I08dbe38f37fa3e8a0f96f71cb6b2dd8737221da5