esp_netif_init() returns standard esp_err_t error code (unlike tcpip_adapter init), so shall be checked for the return value
Also to make the initialization code more consistent.
This change adds a check for compatibility between the nvs version
found on nvs flash and the one assumed by running code during nvs
initialization. Any mismatch is reported to the user using new error
code ESP_ERR_NVS_NEW_VERSION_FOUND.
NVS is used to store PHY calibration data, WiFi configuration, and BT
configuration. Previously BT examples did not call nvs_flash_init,
relying on the fact that it is called during PHY init. However PHY init
did not handle possible NVS initialization errors.
This change moves PHY init procedure into the application, and adds
diagnostic messages to BT config management routines if NVS is not
initialized.
