ASoC: codecs: wcd938x-sdw: Correct Soundwire ports mask

Device has up to WCD938X_MAX_SWR_PORTS number of ports and the array
assigned to prop.src_dpn_prop and prop.sink_dpn_prop has
0..WCD938X_MAX_SWR_PORTS-1 elements.  On the other hand, GENMASK(high,
low) creates an inclusive mask between <high, low>, so we need the mask
from 0 up to WCD938X_MAX_SWR_PORTS-1.

Theoretically, too wide mask could cause an out of bounds read in
sdw_get_slave_dpn_prop() in stream.c, however only in the case of buggy
driver, e.g. adding incorrect number of ports via
sdw_stream_add_slave().

Fixes: 16572522 ("ASoC: codecs: wcd938x-sdw: add SoundWire driver")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20240726-asoc-wcd-wsa-swr-ports-genmask-v1-2-d4d7a8b56f05@linaro.orgSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wcd938x-sdw.c

@@ -1252,12 +1252,12 @@ static int wcd9380_probe(struct sdw_slave *pdev,
 	pdev->prop.lane_control_support = true;
 	pdev->prop.simple_clk_stop_capable = true;
 	if (wcd->is_tx) {
-		pdev->prop.source_ports = GENMASK(WCD938X_MAX_SWR_PORTS, 0);
+		pdev->prop.source_ports = GENMASK(WCD938X_MAX_SWR_PORTS - 1, 0);
 		pdev->prop.src_dpn_prop = wcd938x_dpn_prop;
 		wcd->ch_info = &wcd938x_sdw_tx_ch_info[0];
 		pdev->prop.wake_capable = true;
 	} else {
-		pdev->prop.sink_ports = GENMASK(WCD938X_MAX_SWR_PORTS, 0);
+		pdev->prop.sink_ports = GENMASK(WCD938X_MAX_SWR_PORTS - 1, 0);
 		pdev->prop.sink_dpn_prop = wcd938x_dpn_prop;
 		wcd->ch_info = &wcd938x_sdw_rx_ch_info[0];
 	}