kvm: Add stub for kvm_get_max_memslots()

We'll need the stub soon from memory device context.

While at it, use "unsigned int" as return value and place the
declaration next to kvm_get_free_memslots().

Message-ID: <20230926185738.277351-11-david@redhat.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

accel/stubs/kvm-stub.c

@@ -109,6 +109,11 @@ int kvm_irqchip_remove_irqfd_notifier_gsi(KVMState *s, EventNotifier *n,
     return -ENOSYS;
 }
 
+unsigned int kvm_get_max_memslots(void)
+{
+    return 0;
+}
+
 unsigned int kvm_get_free_memslots(void)
 {
     return 0;