Fix CUSTOM_MATRIX lite matrix_scan return code (#7908)

quantum/matrix_common.c

@@ -103,5 +103,5 @@ __attribute__((weak)) uint8_t matrix_scan(void) {
     debounce(raw_matrix, matrix, MATRIX_ROWS, changed);
 
     matrix_scan_quantum();
-    return 1;
+    return changed;
 }