make KCodeMemory::GetSourceAddress const

Co-authored-by: Mai M. <mathew1800@gmail.com>

src/core/hle/kernel/k_code_memory.h

@@ -46,7 +46,7 @@ public:
     KProcess* GetOwner() const {
         return m_owner;
     }
-    VAddr GetSourceAddress() {
+    VAddr GetSourceAddress() const {
         return m_address;
     }
     size_t GetSize() const {