[sw/testing] Fix result assignment in CHECK_BUFFER

Signed-off-by: Miguel Osorio <miguelosorio@google.com>
diff --git a/sw/device/lib/testing/check.h b/sw/device/lib/testing/check.h
index 3826288..279d8d6 100644
--- a/sw/device/lib/testing/check.h
+++ b/sw/device/lib/testing/check.h
@@ -68,7 +68,7 @@
       }                                                                       \
       result_ = false;                                                        \
     } else {                                                                  \
-      result_ true;                                                           \
+      result_ = true;                                                         \
     }                                                                         \
   } while (false)