ESP8266Audio warning I2S deprecated API

[van_der_decken]

If you read the warnings, they tell you what to do to continue to use the deprecated APIs.

@sergio83100

This set of I2S APIs has been deprecated, please include 'driver/i2s_std.h', 'driver/i2s_pdm.h' or 'driver/i2s_tdm.h' instead. if you want to keep using the old APIs and ignore this warning, you can enable 'Suppress legacy driver deprecated warning' option under 'I2S Configuration' menu in Kconfig