coresight: Discard pm_runtime_put() return values

Failing a debugfs write due to pm_runtime_put() returning a negative
value is not particularly useful.

Returning an error code from pm_runtime_put() merely means that it has
not queued up a work item to check whether or not the device can be
suspended and there are many perfectly valid situations in which that
can happen, like after writing "on" to the devices' runtime PM "control"
attribute in sysfs for one example.  It also happens when the kernel
has been configured with CONFIG_PM unset, in which case
debug_disable_func() in the coresight driver will always return an
error.

For this reason, update debug_disable_func() to simply discard the
return value of pm_runtime_put(), change its return type to void, and
propagate that change to debug_func_knob_write().

This will facilitate a planned change of the pm_runtime_put() return
type to void in the future.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://patch.msgid.link/2058657.yKVeVyVuyW@rafael.j.wysocki

Author: rafaeljw

drivers/hwtracing/coresight/coresight-cpu-debug.c

@@ -451,10 +451,10 @@ static int debug_enable_func(void)
 	return ret;
 }
 
-static int debug_disable_func(void)
+static void debug_disable_func(void)
 {
 	struct debug_drvdata *drvdata;
-	int cpu, ret, err = 0;
+	int cpu;
 
 	/*
 	 * Disable debug power domains, records the error and keep
@@ -466,12 +466,8 @@ static int debug_disable_func(void)
 		if (!drvdata)
 			continue;
 
-		ret = pm_runtime_put(drvdata->dev);
-		if (ret < 0)
-			err = ret;
+		pm_runtime_put(drvdata->dev);
 	}
-
-	return err;
 }
 
 static ssize_t debug_func_knob_write(struct file *f,
@@ -492,7 +488,7 @@ static ssize_t debug_func_knob_write(struct file *f,
 	if (val)
 		ret = debug_enable_func();
 	else
-		ret = debug_disable_func();
+		debug_disable_func();
 
 	if (ret) {
 		pr_err("%s: unable to %s debug function: %d\n",