RW612: SPI loopback testing completely fails

[decsny]

Describe the bug

The SPI loopback test is completely failing almost every case on the RW612 based boards. The test is also failing completely on 4.1.0 and 4.0.0 but in different ways, so I am not sure if this is even a regression, because I can't find a commit where the test doesn't blow up.

Regression

• This is a regression.

Steps to reproduce

west build -b frdm_rw612 -p always tests/drivers/spi/spi_loopback
west flash

Relevant log output

Impact

Major – Severely degrades functionality; workaround is difficult or unavailable.

Environment

No response

Additional Context

No response