soundwire: bus: don't clear SDCA_CASCADE bit

The SDCA_CASCADE bit is a SoundWire 1.2 addition. It is technically in
the DP0_INT register, but SDCA interrupts shall not be handled as part
of the DP0 interrupt processing.

The existing code has clear comments that we don't want to touch the
SDCA_CASCADE bit, but it's actually cleared due to faulty logic dating
from SoundWire 1.0

In theory clearing this bit should have no effect: a cascade bit
remains set while all ORed status are set, but better safe than sorry.

Signed-off-by: Pierre-Louis Bossart <[email protected]>

drivers/soundwire/bus.c

@@ -1474,7 +1474,7 @@ static int sdw_handle_dp0_interrupt(struct sdw_slave *slave, u8 *slave_status)
 	}
 
 	do {
-		clear = status & ~SDW_DP0_INTERRUPTS;
+		clear = status & ~(SDW_DP0_INTERRUPTS | SDW_DP0_SDCA_CASCADE);
 
 		if (status & SDW_DP0_INT_TEST_FAIL) {
 			dev_err(&slave->dev, "Test fail for port 0\n");