Update pinsDebug.h (#9874)

Fix display of analog input value.

Marlin/src/pins/pinsDebug.h

             else
           #endif
           {
-            if (!GET_ARRAY_IS_DIGITAL(pin)) {
+            if (!GET_ARRAY_IS_DIGITAL(x)) {
               sprintf_P(buffer, PSTR("Analog in = %5d"), analogRead(DIGITAL_PIN_TO_ANALOG_PIN(pin)));
               SERIAL_ECHO(buffer);
             }