kernel/vm_manager: Use the VAddr type alias in CarveVMA()

These two variables correspond to address ranges.

src/core/hle/kernel/vm_manager.cpp

@@ -264,8 +264,8 @@ ResultVal<VMManager::VMAIter> VMManager::CarveVMA(VAddr base, u64 size) {
         return ERR_INVALID_ADDRESS_STATE;
     }
 
-    u64 start_in_vma = base - vma.base;
-    u64 end_in_vma = start_in_vma + size;
+    VAddr start_in_vma = base - vma.base;
+    VAddr end_in_vma = start_in_vma + size;
 
     if (end_in_vma > vma.size) {
         // Requested allocation doesn't fit inside VMA