Fix sd_status comparison

Co-Authored-By: perkmeister <perkmeister@users.noreply.github.com>

Marlin/src/lcd/ultralcd.cpp

 
   #if ENABLED(SDSUPPORT) && PIN_EXISTS(SD_DETECT)
 
-    const bool sd_status = IS_SD_INSERTED;
+    const uint8_t sd_status = (uint8_t)IS_SD_INSERTED;
     if (sd_status != lcd_sd_status && lcd_detected()) {
 
-      bool old_sd_status = lcd_sd_status; // prevent re-entry to this block!
+      uint8_t old_sd_status = lcd_sd_status; // prevent re-entry to this block!
       lcd_sd_status = sd_status;
 
       if (sd_status) {