i2c: xiic: skip input clock setup on non-OF systems

Currently Linux does not implement ACPI ClockInput() resource to describe
clocks, unlike DT. However the xiic driver is happy if something
magically enables the clock before the driver probes, and does not
turn it off again. The clock should always be considered optional for
ACPI.

Signed-off-by: Abdurrahman Hussain <abdurrahman@nexthop.ai>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20260223-i2c-xiic-v12-7-b6c9ce4e4f3c@nexthop.ai

Author: abdurrahman-nexthop

drivers/i2c/busses/i2c-xiic.c

@@ -1464,10 +1464,12 @@ static int xiic_i2c_probe(struct platform_device *pdev)
 
 	spin_lock_init(&i2c->atomic_lock);
 
-	i2c->clk = devm_clk_get_enabled(&pdev->dev, NULL);
-	if (IS_ERR(i2c->clk))
-		return dev_err_probe(&pdev->dev, PTR_ERR(i2c->clk),
-				     "failed to enable input clock.\n");
+	if (is_of_node(fwnode)) {
+		i2c->clk = devm_clk_get_enabled(dev, NULL);
+		if (IS_ERR(i2c->clk))
+			return dev_err_probe(dev, PTR_ERR(i2c->clk),
+					"failed to enable input clock.\n");
+	}
 
 	i2c->dev = dev;