proper use of module enable/disable to reset counters

[guruofquality]

Currently time counters are reset strategically via GPIO to maintain a tx/rx time relationship. We should be able to do this by performing a disable/enable module sequence instead.

    //reset the counters with GPIO and stash the offset
    //this is the same as setting the time because
    //we maintain the offset math within the driver

    int ret = 0;
    uint32_t original = 0;
    ret |= bladerf_config_gpio_read(_dev, &original);
    ret |= bladerf_config_gpio_write(_dev, original & ~(BLADERF_GPIO_TIMESTAMP));
    ret |= bladerf_config_gpio_write(_dev, original | BLADERF_GPIO_TIMESTAMP);