[media] smiapp: Make clock control optional

The clock control is not explicitly controlled by the driver in two cases:
ACPI based systems and when the clock is part of the power sequence of the
camera module.

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/i2c/smiapp/smiapp-core.c

@@ -2892,7 +2892,10 @@ static int smiapp_probe(struct i2c_client *client,
 	}
 
 	sensor->ext_clk = devm_clk_get(&client->dev, NULL);
-	if (IS_ERR(sensor->ext_clk)) {
+	if (PTR_ERR(sensor->ext_clk) == -ENOENT) {
+		dev_info(&client->dev, "no clock defined, continuing...\n");
+		sensor->ext_clk = NULL;
+	} else if (IS_ERR(sensor->ext_clk)) {
 		dev_err(&client->dev, "could not get clock (%ld)\n",
 			PTR_ERR(sensor->ext_clk));
 		return -EPROBE_DEFER;