🔧 Update fan 0 conflict check

Followup to MarlinFirmware#25568

Author: thinkyhead

Marlin/src/inc/SanityCheck.h

@@ -3744,7 +3744,7 @@ static_assert(_PLUS_TEST(3), "DEFAULT_MAX_ACCELERATION values must be positive."
       #error "SPINDLE_LASER_PWM_PIN conflicts with E6_AUTO_FAN_PIN."
     #elif _PIN_CONFLICT(E7_AUTO_FAN)
       #error "SPINDLE_LASER_PWM_PIN conflicts with E7_AUTO_FAN_PIN."
-    #elif _PIN_CONFLICT(FAN)
+    #elif _PIN_CONFLICT(FAN0)
       #error "SPINDLE_LASER_PWM_PIN conflicts with FAN0_PIN."
     #elif _PIN_CONFLICT(FAN1)
       #error "SPINDLE_LASER_PWM_PIN conflicts with FAN1_PIN."