Use flash size from board manifest by default // Resolve platformio#300

Author: valeros

builder/main.py

@@ -368,7 +368,7 @@ def __fetch_fs_size(target, source, env):
             "write_flash", "-z",
             "--flash_mode", "${__get_board_flash_mode(__env__)}",
             "--flash_freq", "${__get_board_f_flash(__env__)}",
-            "--flash_size", "detect",
+            "--flash_size", board.get("upload.flash_size", "detect"),
             board.get("upload.offset_address", "$ESP32_APP_OFFSET"),
             "$SOURCE"
         ],