GR flowgraph update

`Symbol Sync` block is now better tuned to M17 signals

SP5WWP/grc/simple_rx.grc

@@ -293,8 +293,8 @@ blocks:
     comment: ''
     constellation: digital.constellation_bpsk().base()
     damping: '1.0'
-    loop_bw: '0.0045'
-    max_dev: '4.5'
+    loop_bw: 2.0*math.pi*0.0015
+    max_dev: '0.05'
     maxoutbuf: '0'
     minoutbuf: '0'
     nfilters: '128'