🐛 Spellcheck comments (#22496)

codespell -q 3 --builtin=clear,rare,informal,code -S ./Marlin/src/lcd/language -L alo,amin,endcode,stdio,uint

Marlin/src/HAL/LINUX/hardware/Heater.cpp

@@ -54,7 +54,7 @@ void Heater::update() {
 }
 
 void Heater::interrupt(GpioEvent ev) {
-  // ununsed
+  // unused
 }
 
 #endif // __PLAT_LINUX__