mm: adding speculative page fault failure trace events

This patch a set of new trace events to collect the speculative page fault
event failures.

Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>
Change-Id: I9dafba293edf40bdad4ae241d105ecdfb42579c1
Patch-mainline: linux-mm @ Tue, 17 Apr 2018 16:33:25
[vinmenon@codeaurora.org: trivial merge conflicts]
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>