profile_manager: Make array parameter to CreateNewUser a const reference

This doesn't modify the passed in array, so this can be a const
reference.

src/core/hle/service/acc/profile_manager.cpp

@@ -62,7 +62,7 @@ ResultCode ProfileManager::AddUser(ProfileInfo user) {
 
 /// Create a new user on the system. If the uuid of the user already exists, the user is not
 /// created.
-ResultCode ProfileManager::CreateNewUser(UUID uuid, std::array<u8, 0x20>& username) {
+ResultCode ProfileManager::CreateNewUser(UUID uuid, const std::array<u8, 0x20>& username) {
     if (user_count == MAX_USERS) {
         return ERROR_TOO_MANY_USERS;
     }

src/core/hle/service/acc/profile_manager.h

@@ -79,7 +79,7 @@ class ProfileManager {
 public:
     ProfileManager(); // TODO(ogniK): Load from system save
     ResultCode AddUser(ProfileInfo user);
-    ResultCode CreateNewUser(UUID uuid, std::array<u8, 0x20>& username);
+    ResultCode CreateNewUser(UUID uuid, const std::array<u8, 0x20>& username);
     ResultCode CreateNewUser(UUID uuid, const std::string& username);
     boost::optional<size_t> GetUserIndex(const UUID& uuid) const;
     boost::optional<size_t> GetUserIndex(ProfileInfo user) const;