asoc: codecs: Add proper NULL checks and initialize variables

Add null checks and initialize unintialized variables in
wsa macro, wcd937x and wcd937x_slave drivers.

CRs-Fixed: 2328286
Change-Id: I76b8d262e42d2b06ece3a6ecba28ed26b13d4447
Signed-off-by: Tanya Dixit <tdixit@codeaurora.org>

asoc/codecs/wcd937x/wcd937x_slave.c

@@ -31,6 +31,11 @@ static int wcd937x_slave_bind(struct device *dev,
 	uint8_t devnum = 0;
 	struct swr_device *pdev = to_swr_device(dev);
 
+	if (pdev == NULL) {
+		dev_err(dev, "%s: pdev is NULL\n", __func__);
+		return -EINVAL;
+	}
+
 	wcd937x_slave = devm_kzalloc(&pdev->dev,
 				sizeof(struct wcd937x_slave_priv), GFP_KERNEL);
 	if (!wcd937x_slave)
@@ -59,6 +64,11 @@ static void wcd937x_slave_unbind(struct device *dev,
 	struct wcd937x_slave_priv *wcd937x_slave = NULL;
 	struct swr_device *pdev = to_swr_device(dev);
 
+	if (pdev == NULL) {
+		dev_err(dev, "%s: pdev is NULL\n", __func__);
+		return;
+	}
+
 	wcd937x_slave = swr_get_dev_data(pdev);
 	if (!wcd937x_slave) {
 		dev_err(&pdev->dev, "%s: wcd937x_slave is NULL\n", __func__);