Kernel/riscv64: Stub out Processor::set_thread_specific_data

Author: https://github.com/spholz
Commit: 2f33e7a964
Pull-request: https://github.com/SerenityOS/serenity/pull/23113
Reviewed-by: https://github.com/ADKaster ✅

Kernel/Arch/riscv64/Processor.cpp

@@ -295,7 +295,7 @@ StringView ProcessorBase<T>::platform_string()
 template<typename T>
 void ProcessorBase<T>::set_thread_specific_data(VirtualAddress)
 {
-    TODO_RISCV64();
+    // FIXME: Add support for thread-local storage on RISC-V
 }
 
 template<typename T>