extmod/modonewire: Adopt Maxim recommended read timings.

The timing of the onewire module was way too fast when reading.  This
commit adopts read timings as recommended in Maxim application note 126:
6 us (pulse) / 9 us (sample) / 55 us (bit slot).  See also:
https://www.analog.com/en/technical-articles/1wire-communication-through-software.html

Signed-off-by: Damien George <damien@micropython.org>

extmod/modonewire.c

@@ -38,9 +38,9 @@
 #define TIMING_RESET1 (480)
 #define TIMING_RESET2 (70)
 #define TIMING_RESET3 (410)
-#define TIMING_READ1 (5)
-#define TIMING_READ2 (5)
-#define TIMING_READ3 (40)
+#define TIMING_READ1  (6)
+#define TIMING_READ2  (9)
+#define TIMING_READ3  (55)
 #define TIMING_WRITE1 (10)
 #define TIMING_WRITE2 (50)
 #define TIMING_WRITE3 (10)