tests: drivers: uart: async_dual: Extend testing

Extend test with a mode where HWFC is off and receiver is providing
buffers on time. In that case receiver should be able to continuously
receive data without losing any byte (even without HWFC). Additionally,
TX data is chopped to verify that receiver does not loose bytes when
new TX data collides with detected RX timeout.

Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>
3 files changed