KVM: Return '0' directly when there's no task to yield to

Do "return 0" instead of initializing and returning a local variable in
kvm_vcpu_yield_to(), e.g. so that it's more obvious what the function
returns if there is no task.

No functional change intended.

Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240802200136.329973-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: sean-jc

virt/kvm/kvm_main.c

@@ -3772,15 +3772,15 @@ int kvm_vcpu_yield_to(struct kvm_vcpu *target)
 {
 	struct pid *pid;
 	struct task_struct *task = NULL;
-	int ret = 0;
+	int ret;
 
 	rcu_read_lock();
 	pid = rcu_dereference(target->pid);
 	if (pid)
 		task = get_pid_task(pid, PIDTYPE_PID);
 	rcu_read_unlock();
 	if (!task)
-		return ret;
+		return 0;
 	ret = yield_to(task, 1);
 	put_task_struct(task);