[sr-dev] [kamailio/kamailio] wrong code for new mod param of pdt module (Issue #3626)

### Description

This new code in pdttree.c is not correct for this new pdt mode, it just print's a debug log instead of error. The return value should be 0 instead of 1 in case _pdt_mode is 1 otherwise it will still not start. <code> if(_pdt_mode & 1) { LM_DBG("prefix already allocated [%.*s/[%.*s] - ignoring\n", sp->len, sp->s, sd->len, sd->s); return -1; } else { LM_ERR("prefix already allocated [%.*s/[%.*s]\n", sp->len, sp->s, sd->len, sd->s); return -1; } </code>

### Troubleshooting

#### Reproduction

#### Debugging Data

#### Log Messages

#### SIP Traffic

### Possible Solutions

### Additional Information

* **Operating System**: