hp: fix [-Wunused-but-set-variable] compiler warnings

backend/hp-scl.c

@@ -1338,13 +1338,11 @@ static SANE_Status
 process_data (PROCDATA_HANDLE *ph, unsigned char *read_ptr, int nread)
 
 {int bytes_left;
- HpProcessData *procdata;
 
  if (nread <= 0) return SANE_STATUS_GOOD;
 
  if (ph == NULL) return SANE_STATUS_INVAL;
 
- procdata = &(ph->procdata);
  if ( ph->tmp_buf_len > 0 )  /* Something left ? */
  {
    bytes_left = ph->tmp_buf_size - ph->tmp_buf_len;

backend/hp.c

@@ -468,13 +468,11 @@ static void
 hp_device_info_remove (void)
 {
  HpDeviceInfoList  next, infolistelement = global.infolist;
- HpDeviceInfo *info;
 
  if (!global.is_up) return;
 
  while (infolistelement)
  {
-   info = &(infolistelement->info);
    next = infolistelement->next;
    sanei_hp_free (infolistelement);
    infolistelement = next;