mm/migration: add trace events for THP migrations

Patch series "mm/migration: Add trace events", v3.

This adds trace events for all migration scenarios including base page,
THP and HugeTLB.

This patch (of 3):

This adds two trace events for PMD based THP migration without split.
These events closely follow the implementation details like setting and
removing of PMD migration entries, which are essential operations for THP
migration.  This moves CREATE_TRACE_POINTS into generic THP from powerpc
for these new trace events to be available on other platforms as well.

Link: https://lkml.kernel.org/r/1643368182-9588-1-git-send-email-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/1643368182-9588-2-git-send-email-anshuman.khandual@arm.com


Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>