driver-core: cpu: Make isolate node read-only

We no longer support isolating a core using the isolate node. Remove
write-access to this node.

Change-Id: I89d7b0d7f1c560fefac833e1fc165312a61cf3aa
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>
Signed-off-by: Satya Durga Srinivasu Prabhala <satyap@codeaurora.org>

drivers/base/cpu.c

@@ -183,8 +183,8 @@ static struct attribute_group crash_note_cpu_attr_group = {
 
 #ifdef CONFIG_HOTPLUG_CPU
 
-static ssize_t show_cpu_isolated(struct device *dev,
-				struct device_attribute *attr, char *buf)
+static ssize_t isolate_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
 {
 	struct cpu *cpu = container_of(dev, struct cpu, dev);
 	ssize_t rc;
@@ -196,31 +196,7 @@ static ssize_t show_cpu_isolated(struct device *dev,
 	return rc;
 }
 
-static ssize_t __ref store_cpu_isolated(struct device *dev,
-				struct device_attribute *attr,
-				const char *buf, size_t count)
-{
-	struct cpu *cpu = container_of(dev, struct cpu, dev);
-	int err;
-	int cpuid = cpu->dev.id;
-	unsigned int isolated;
-
-	err = kstrtouint(strstrip((char *)buf), 0, &isolated);
-	if (err)
-		return err;
-
-	if (isolated > 1)
-		return -EINVAL;
-
-	if (isolated)
-		sched_isolate_cpu(cpuid);
-	else
-		sched_unisolate_cpu(cpuid);
-
-	return count;
-}
-
-static DEVICE_ATTR(isolate, 0644, show_cpu_isolated, store_cpu_isolated);
+static DEVICE_ATTR_RO(isolate);
 
 static struct attribute *cpu_isolated_attrs[] = {
 	&dev_attr_isolate.attr,