mclk now generated by ps not axi clkgen ip. ADAU1761 expects a free
running clock and the i2s driver was switching the axi clkgen ip off
which was causing issues.
Observation and RX should never run at the same time.
Given that there is no FIFO on the RX and OBS paths, they will use the higheste performance HP ports, which are HP1 and HP2