🔧 Fix IDEX home check

Followup to MarlinFirmware#25780

Author: thinkyhead

Marlin/src/inc/SanityCheck.h

@@ -1822,7 +1822,7 @@ static_assert(COUNT(arm) == LOGICAL_AXES, "AXIS_RELATIVE_MODES must contain " _L
   #elif !defined(X2_HOME_POS) || !defined(X2_MIN_POS) || !defined(X2_MAX_POS)
     #error "DUAL_X_CARRIAGE requires X2_HOME_POS, X2_MIN_POS, and X2_MAX_POS."
   #elif X_HOME_TO_MAX
-    #error "DUAL_X_CARRIAGE requires X_HOME_DIR 1."
+    #error "DUAL_X_CARRIAGE requires X_HOME_DIR -1."
   #endif
 #endif