Kernel: Remove declarations for non-existent methods

Author: https://github.com/AtkinsSJ
Commit: 3cbc0fdbb0
Pull-request: https://github.com/SerenityOS/serenity/pull/17203
Reviewed-by: https://github.com/linusg ✅

Kernel/CommandLine.h

@@ -100,7 +100,6 @@ public:
     [[nodiscard]] NonnullOwnPtrVector<KString> userspace_init_args() const;
     [[nodiscard]] StringView root_device() const;
     [[nodiscard]] bool is_nvme_polling_enabled() const;
-    [[nodiscard]] bool is_i8042_force_scan_code_2() const;
     [[nodiscard]] size_t switch_to_tty() const;
 
 private: