khugepaged: pass folio instead of head page to trace events

khugepaged: pass folio instead of head page to trace events

The trace functions trace_mm_collapse_huge_page_isolate() and
trace_mm_khugepaged_scan_pmd() each have a single user, which always
passes in the head page of a folio.  Refactor both functions to take a
folio directly.

Link: https://lkml.kernel.org/r/20250425002425.533698-1-nifan.cxl@gmail.com
Signed-off-by: Fan Ni <fan.ni@samsung.com>
Reviewed-by: Nico Pache <npache@redhat.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Yang Shi <yang@os.amperecomputing.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Adam Manzanares <a.manzanares@samsung.com>
Cc: Luis Chamberalin <mcgrof@kernel.org>
Cc: Mariano Pache <npache@redhat.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>