virt/kvm: Replace spin_is_locked() with lockdep

lockdep_assert_held() is better suited to checking locking requirements,
since it only checks if the current thread holds the lock regardless of
whether someone else does. This is also a step towards possibly removing
spin_is_locked().

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: <kvm@vger.kernel.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>

virt/kvm/kvm_main.c

@@ -4083,7 +4083,7 @@ static int kvm_suspend(void)
 static void kvm_resume(void)
 {
 	if (kvm_usage_count) {
-		WARN_ON(raw_spin_is_locked(&kvm_count_lock));
+		lockdep_assert_held(&kvm_count_lock);
 		hardware_enable_nolock(NULL);
 	}
 }