esp32/machine_i2c: Use IDF function for calculating main timeout.

The esp32 I2C driver sets a global timeout during init.  The functionality
for this is currently only correct for original esp32 and esp32-s2, newer
parts have a slightly different argument which is log-base-2 of the
timeout.

Note that `i2c_set_timeout()` is a thin layer around `i2c_ll_set_tout()`
with the latter writing directly to the hardware register.  So the timeout
argument passed to `i2c_set_timeout()` needs to be in units calculated by
`i2c_ll_calculate_timeout_us_to_reg_val()`.

Signed-off-by: Andrew Leech <andrew.leech@planetinnovation.com.au>

ports/esp32/machine_i2c.c

@@ -257,7 +257,7 @@ static void machine_hw_i2c_init(machine_hw_i2c_obj_t *self, bool first_init) {
         .master.clk_speed = self->freq,
     };
     i2c_param_config(self->port, &conf);
-    int timeout = I2C_SCLK_FREQ / 1000000 * self->timeout_us;
+    int timeout = i2c_ll_calculate_timeout_us_to_reg_val(I2C_SCLK_FREQ, self->timeout_us);
     i2c_set_timeout(self->port, (timeout > I2C_LL_MAX_TIMEOUT) ? I2C_LL_MAX_TIMEOUT : timeout);
     i2c_driver_install(self->port, I2C_MODE_MASTER, 0, 0, 0);
 }