KVM: Return directly after a failed copy_from_user() in kvm_vm_compat_ioctl()

* Return directly after a call of the function "copy_from_user" failed
  in a case block.

  This issue was detected by using the Coccinelle software.

* Delete the jump label "out" which became unnecessary with
  this refactoring.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

virt/kvm/kvm_main.c

@@ -3148,10 +3148,9 @@ static long kvm_vm_compat_ioctl(struct file *filp,
 		struct compat_kvm_dirty_log compat_log;
 		struct kvm_dirty_log log;
 
-		r = -EFAULT;
 		if (copy_from_user(&compat_log, (void __user *)arg,
 				   sizeof(compat_log)))
-			goto out;
+			return -EFAULT;
 		log.slot	 = compat_log.slot;
 		log.padding1	 = compat_log.padding1;
 		log.padding2	 = compat_log.padding2;
@@ -3163,8 +3162,6 @@ static long kvm_vm_compat_ioctl(struct file *filp,
 	default:
 		r = kvm_vm_ioctl(filp, ioctl, arg);
 	}
-
-out:
 	return r;
 }
 #endif