Suppress unused var warning

Marlin/src/lcd/menu/menu_temperature.cpp

@@ -97,7 +97,9 @@ void Temperature::lcd_preheat(const int16_t e, const int8_t indh, const int8_t i
 
     #if HOTENDS == 1
       PGM_P msg_preheat[] = ARRAY_N(PREHEAT_COUNT, GET_TEXT(MSG_PREHEAT_1), GET_TEXT(MSG_PREHEAT_2), GET_TEXT(MSG_PREHEAT_3), GET_TEXT(MSG_PREHEAT_4), GET_TEXT(MSG_PREHEAT_5));
+      #if HAS_HEATED_BED
         PGM_P msg_preheat_end[] = ARRAY_N(PREHEAT_COUNT, GET_TEXT(MSG_PREHEAT_1_END), GET_TEXT(MSG_PREHEAT_2_END), GET_TEXT(MSG_PREHEAT_3_END), GET_TEXT(MSG_PREHEAT_4_END), GET_TEXT(MSG_PREHEAT_5_END));
+      #endif
     #elif HAS_MULTI_HOTEND
       PGM_P msg_preheat_all[] = ARRAY_N(PREHEAT_COUNT, GET_TEXT(MSG_PREHEAT_1_ALL), GET_TEXT(MSG_PREHEAT_2_ALL), GET_TEXT(MSG_PREHEAT_3_ALL), GET_TEXT(MSG_PREHEAT_4_ALL), GET_TEXT(MSG_PREHEAT_5_ALL));
     #endif