chunkserver: Fix reporting disks to the CGI interface

This bug fixes chunkserver which used to send malformed
CLTOCL_HDD_LIST_V2 message which couldn't be interpreted by the CGI
interface resulting in no disk usage statistics and a possibility not to
show more than one disk per chunkserver. This bug didn't affect
lizardfs-probe in any way, because it ignores the broken field.

Change-Id: I2d1e400b7c9672d5a4a6e68f6fb5e53303d4d4a6