php-fpm: remove config comments to fix startup

The comments in the Buildroot-provided php-fpm.conf would produce the
following error when starting php-fpm:

ERROR: [/etc/php-fpm.conf:2] value is NULL for a ZEND_INI_PARSER_ENTRY

Removing the comments fixes the problem.

Signed-off-by: Frank Hunleth <fhunleth@troodon-software.com>
Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>