mmu: remove obsolete EEPROM comments

Firmware/mmu2.cpp

@@ -55,7 +55,7 @@ MMU2::MMU2()
 void MMU2::Start() {
     mmu2Serial.begin(MMU_BAUD);
 
-    PowerOn();          // I repurposed this to serve as our EEPROM disable toggle.
+    PowerOn();
     mmu2Serial.flush(); // make sure the UART buffer is clear before starting communication
 
     extruder = MMU2_NO_TOOL;

Firmware/mmu2_power.cpp

@@ -7,8 +7,7 @@
 
 namespace MMU2 {
 
-// sadly, on MK3 we cannot do actual power cycle on HW...
-// so we just block the MMU via EEPROM var instead.
+// On MK3 we cannot do actual power cycle on HW. Instead trigger a hardware reset.
 void power_on() {
 #ifdef MMU_HWRESET
     WRITE(MMU_RST_PIN, 1);