cmd: clk: Handle ENODEV from clk_get_rate

clk_get_rate may return -ENODEV if the clock isn't valid.

Also, make the error cases go through a single path.

Fixes: ff8eee0330a6 ("cmd: clk: Add trivial implementation of clock dump
	for DM")

Signed-off-by: Ismael Luceno <ismael.luceno@silicon-gears.com>
Reviewed-by: Matthias Brugger <mbrugger@suse.com>
Reviewed-by: Marek Vasut <marek.vasut@gmail.com>
diff --git a/cmd/clk.c b/cmd/clk.c
index fd42315..5402c87 100644
--- a/cmd/clk.c
+++ b/cmd/clk.c
@@ -17,6 +17,7 @@
 	struct uclass *uc;
 	struct clk clk;
 	int ret;
+	ulong rate;
 
 	/* Device addresses start at 1 */
 	ret = uclass_get(UCLASS_CLK, &uc);
@@ -26,20 +27,23 @@
 	uclass_foreach_dev(dev, uc) {
 		memset(&clk, 0, sizeof(clk));
 		ret = device_probe(dev);
-		if (ret) {
-			printf("%-30.30s : ? Hz\n", dev->name);
-			continue;
-		}
+		if (ret)
+			goto noclk;
 
 		ret = clk_request(dev, &clk);
-		if (ret) {
-			printf("%-30.30s : ? Hz\n", dev->name);
-			continue;
-		}
+		if (ret)
+			goto noclk;
 
-		printf("%-30.30s : %lu Hz\n", dev->name, clk_get_rate(&clk));
-
+		rate = clk_get_rate(&clk);
 		clk_free(&clk);
+
+		if (rate == -ENODEV)
+			goto noclk;
+
+		printf("%-30.30s : %lu Hz\n", dev->name, rate);
+		continue;
+	noclk:
+		printf("%-30.30s : ? Hz\n", dev->name);
 	}
 
 	return 0;