Save PROGMEM on serial prefixes (#12033)

With default config and `EEPROM_SETTINGS`, saves over 200 bytes of PROGMEM.

Marlin/src/HAL/HAL_LPC1768/HAL.cpp

@@ -75,13 +75,13 @@ void HAL_adc_init(void) {
 #include "../../core/language.h"
 
 extern void kill(PGM_P);
-extern const char errormagic[];
 
 void HAL_adc_enable_channel(int ch) {
   pin_t pin = analogInputToDigitalPin(ch);
 
   if (pin == -1) {
-    SERIAL_PRINTF("%sINVALID ANALOG PORT:%d\n", errormagic, ch);
+    serial_error_start();
+    SERIAL_PRINTF("INVALID ANALOG PORT:%d\n", ch);
     kill(MSG_KILLED);
   }