smb3: Add tracepoints for read, write and query_dir enter

Allows tracing begin (not just completion) of read, write
and query_dir which may be helpful in finding slow requests
and other timing information

Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>