Conigure UART to use 2 stop bits and even parity
in 'dual transmission' case
to cover more driver code cases.
Signed-off-by: Bartosz Miller <bartosz.miller@nordicsemi.no>
UART error may be reported with random timing
from either UART in configuration mismatch case.
The test case is now aligned to such behaviour.
Signed-off-by: Bartosz Miller <bartosz.miller@nordicsemi.no>