Fix compilation errors. Followup to #12439 (#12481)

Marlin/src/lcd/extensible_ui/ui_api.cpp

       // The ms count is
       return (uint32_t)(currTime / (F_CPU / 8000));
     }
-
   #endif // __SAM3X8E__
 
   void delay_us(unsigned long us) {

Marlin/src/lcd/extensible_ui/ui_api.h

   #ifdef __SAM3X8E__
     uint32_t safe_millis();
   #else
-    #define safe_millis() millis() // TODO: Implement for AVR
+    FORCE_INLINE uint32_t safe_millis() { return millis(); } // TODO: Implement for AVR
   #endif
 
   void delay_us(unsigned long us);

Marlin/src/lcd/ultralcd.cpp

   #if ENABLED(SDSUPPORT)
     #include "../sd/cardreader.h"
   #endif
-
   #if ENABLED(EXTENSIBLE_UI)
     #define START_OF_UTF8_CHAR(C) (((C) & 0xC0u) != 0x80u)
   #endif
 #endif
 
 #if HAS_SPI_LCD
+  #if ENABLED(STATUS_MESSAGE_SCROLLING)
+    uint8_t MarlinUI::status_scroll_offset; // = 0
+    #if LONG_FILENAME_LENGTH > CHARSIZE * 2 * (LCD_WIDTH)
+      #define MAX_MESSAGE_LENGTH LONG_FILENAME_LENGTH
+    #else
+      #define MAX_MESSAGE_LENGTH CHARSIZE * 2 * (LCD_WIDTH)
+    #endif
+  #else
+    #define MAX_MESSAGE_LENGTH CHARSIZE * (LCD_WIDTH)
+  #endif
+#elif ENABLED(EXTENSIBLE_UI)
+  #define MAX_MESSAGE_LENGTH 63
+#endif
+
+#ifdef MAX_MESSAGE_LENGTH
+  uint8_t MarlinUI::status_message_level; // = 0
+  char MarlinUI::status_message[MAX_MESSAGE_LENGTH + 1];
+#endif
+
+#if HAS_SPI_LCD
 
 #if HAS_GRAPHICAL_LCD
   #include "dogm/ultralcd_DOGM.h"
   uint8_t lcd_sd_status;
 #endif
 
-#if ENABLED(STATUS_MESSAGE_SCROLLING)
-  uint8_t MarlinUI::status_scroll_offset; // = 0
-  #if LONG_FILENAME_LENGTH > CHARSIZE * 2 * (LCD_WIDTH)
-    #define MAX_MESSAGE_LENGTH LONG_FILENAME_LENGTH
-  #else
-    #define MAX_MESSAGE_LENGTH CHARSIZE * 2 * (LCD_WIDTH)
-  #endif
-#elif ENABLED(EXTENSIBLE_UI)
-  #define MAX_MESSAGE_LENGTH 63
-#else
-  #define MAX_MESSAGE_LENGTH CHARSIZE * (LCD_WIDTH)
-#endif
-
-#if HAS_SPI_LCD || ENABLED(EXTENSIBLE_UI)
-  uint8_t MarlinUI::status_message_level; // = 0
-  char MarlinUI::status_message[MAX_MESSAGE_LENGTH + 1];
-#endif
-
 #if HAS_LCD_MENU && LCD_TIMEOUT_TO_STATUS
   bool MarlinUI::defer_return_to_status;
 #endif