try to edit suphp configuration file
/usr/local/etc/suphp.conf:
logfile=/usr/local/apache/logs/suphp_log
loglevel=info
logfile:
Specifies path to logfile. If not specified, the compile-time value is
used.
loglevel:
One of "info", "warn", "error", "none".
Specifies messages of which classification should be logged.
Defaults to "info".
so by this instructions you would need to replace "loglevel=info" to "loglevel=none" in the file /usr/local/etc/suphp.conf.