sm_io/*/sm_ch_si57x.c: use 300ms when resetting Si57x to inital configuration

Sometimes, only 30ms is not enough to si57x to reset
(maybe we are a bit oo fast on waiting). So, we use 300ms
and everything worked again.

src/sm_io/chips/sm_ch_si57x.c

@@ -394,8 +394,8 @@ static smch_err_e _smch_si57x_get_defaults (smch_si57x_t *self, double fout)
     uint8_t data = SI57X_CONTROL_RECALL;
     _smch_si57x_write_8 (self, SI57X_REG_CONTROL, &data);
 
-    /* Si57x takes up to 30ms to return to initial conditions */
-    SMCH_SI57X_WAIT(30000);
+    /* Si57x takes up to 30ms to return to initial conditions. To be safe, use 300ms */
+    SMCH_SI57X_WAIT(300000);
 
     /* Read dividers */
     err = _smch_si57x_get_divs (self, &self->rfreq, &self->n1, &self->hs_div);