Tweak IS_SD_INSERTED

Marlin/src/sd/cardreader.h

   #define IS_SD_INSERTED() Sd2Card::isInserted()
 #elif PIN_EXISTS(SD_DETECT)
   #if ENABLED(SD_DETECT_INVERTED)
-    #define IS_SD_INSERTED() (READ(SD_DETECT_PIN) == HIGH)
+    #define IS_SD_INSERTED()  READ(SD_DETECT_PIN)
   #else
-    #define IS_SD_INSERTED() (READ(SD_DETECT_PIN) == LOW)
+    #define IS_SD_INSERTED() !READ(SD_DETECT_PIN)
   #endif
 #else
   // No card detect line? Assume the card is inserted.