ldr: Mark IsValidNROHash() as a const member function

This doesn't modify instance state, so it can be made const.

src/core/hle/service/ldr/ldr.cpp

@@ -480,9 +480,8 @@ private:
     std::map<VAddr, NROInfo> nro;
     std::map<VAddr, std::vector<SHA256Hash>> nrr;
 
-    bool IsValidNROHash(const SHA256Hash& hash) {
-        return std::any_of(
-            nrr.begin(), nrr.end(), [&hash](const std::pair<VAddr, std::vector<SHA256Hash>>& p) {
+    bool IsValidNROHash(const SHA256Hash& hash) const {
+        return std::any_of(nrr.begin(), nrr.end(), [&hash](const auto& p) {
             return std::find(p.second.begin(), p.second.end(), hash) != p.second.end();
         });
     }