mm/khugepaged: refactor mm_khugepaged_scan_file tracepoint to remove filename from function call

Refactor the mm_khugepaged_scan_file tracepoint to move filename
dereference to the tracepoint definition, to maintain consistency with
other tracepoints[1].

[1]:lore.kernel.org/lkml/20221024111621.3ba17e2c@gandalf.local.home/

Link: https://lkml.kernel.org/r/20221026044524.54793-1-gautammenghani201@gmail.com
Fixes: d41fd201

 ("mm/khugepaged: add tracepoint to hpage_collapse_scan_file()")
Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>