L2SDP-436, add comment

src/periph/fpga.cpp

@@ -77,9 +77,9 @@ Periph_fpga::Periph_fpga(uint global_nr, string ipaddr, uint n_beamsets):
     my_jesd_csr_dev_syncn {0},
     my_jesd_rx_err0 {0},
     my_jesd_rx_err1 {0},
-    my_pps_offset_cnt(0),
     my_signal_input_mean {0.0},
     my_signal_input_rms {0.0},
+    my_pps_offset_cnt(0),
     my_pps_expected_cnt(0),
     my_pps_present(false),
     my_pps_capture_cnt(0)

src/periph/fpga.h

@@ -72,11 +72,11 @@ private:
   uint32_t my_jesd_rx_err0[C_S_pn];
   uint32_t my_jesd_rx_err1[C_S_pn];
   bool    my_xst_processing_enable;
-  uint32_t my_pps_offset_cnt;
 
   double my_signal_input_mean[C_S_pn];
   double my_signal_input_rms[C_S_pn];
 
+  uint32_t my_pps_offset_cnt;  // used by read_time_since_last_pps()
   uint32_t my_pps_expected_cnt;
   bool     my_pps_present;
   uint32_t my_pps_capture_cnt;