Reduce clamp threshold to 2MB (#3034)

A proposed solution to the non-GPU memory asserts seen in RESIDENT EVIL 2 (CUSA09193)

src/core/memory.cpp

@@ -68,7 +68,7 @@ void MemoryManager::SetupMemoryRegions(u64 flexible_size, bool use_extended_mem1
 }
 
 u64 MemoryManager::ClampRangeSize(VAddr virtual_addr, u64 size) {
-    static constexpr u64 MinSizeToClamp = 512_MB;
+    static constexpr u64 MinSizeToClamp = 2_MB;
     // Dont bother with clamping if the size is small so we dont pay a map lookup on every buffer.
     if (size < MinSizeToClamp) {
         return size;