[Kernel] Remove item limit from enumerators, fixes #1255

Like said in that issue, it seems the limit passed to XamContentCreateEnumerator is actually a limit on how many results XamEnumerate should return per call, not a limit on the number of enumeration items in total.
These changes fix Sonic Unleashed not loading more than 1 DLC (it passes 1 as the limit, but then loops over XamEnumerate to load in each DLC one at a time), and likely many other games.

src/xenia/kernel/xenumerator.cc

@@ -12,10 +12,10 @@
 namespace xe {
 namespace kernel {
 
-XEnumerator::XEnumerator(KernelState* kernel_state, size_t item_capacity,
+XEnumerator::XEnumerator(KernelState* kernel_state, size_t items_per_enumerate,
                          size_t item_size)
     : XObject(kernel_state, kTypeEnumerator),
-      item_capacity_(item_capacity),
+      items_per_enumerate_(items_per_enumerate),
       item_size_(item_size) {}
 
 XEnumerator::~XEnumerator() = default;