code: Use std::span where appropriate (#6658)

* code: Use std::span when possible

* code: Prefix memcpy and memcmp with std::

src/core/hle/ipc_helpers.h

@@ -38,7 +38,7 @@ public:
 
     void Skip(unsigned size_in_words, bool set_to_null) {
         if (set_to_null)
-            memset(cmdbuf + index, 0, size_in_words * sizeof(u32));
+            std::memset(cmdbuf + index, 0, size_in_words * sizeof(u32));
         index += size_in_words;
     }
 };