media: i2c: ov5670: Properly handle !CONFIG_HAVE_CLK

The ov5670 driver tries to get a reference to the xvclk provider by using
the common cock framework and deflects to parsing the "clock-frequency"
property in case the clock provider is not specified in the firmware
interface, detected by checking if ov5670->xvclk == PTR_ERR(-ENOENT).

However, as reported by the Smatch static checker, if CONFIG_HAVE_CLK is
not enabled, devm_clk_get() returns 0 which when passed to PTR_ERR()
means success causing the driver to fail without propagating any error
code up.

Explicitly handle the case where ov5670->xvclk it set to NULL, forcing
the code to parse the "clock-frequency" property in case CONFIG_HAVE_CLK
is not enabled, as suggested by Dan Carpenter.
Reported-by: Dan Carpenter <error27@gmail.com>
Suggested-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

drivers/media/i2c/ov5670.c

@@ -2694,7 +2694,7 @@ static int ov5670_probe(struct i2c_client *client)
 	ov5670->xvclk = devm_clk_get(&client->dev, NULL);
 	if (!IS_ERR_OR_NULL(ov5670->xvclk))
 		input_clk = clk_get_rate(ov5670->xvclk);
-	else if (PTR_ERR(ov5670->xvclk) == -ENOENT)
+	else if (!ov5670->xvclk || PTR_ERR(ov5670->xvclk) == -ENOENT)
 		device_property_read_u32(&client->dev, "clock-frequency",
 					 &input_clk);
 	else