Update default serial upload speed

Author: valeros

boards/esp32-devkitlipo.json

@@ -28,7 +28,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.olimex.com/Products/IoT/ESP32/ESP32-DevKit-LiPo/open-source-hardware",
   "vendor": "OLIMEX"

boards/esp32-poe-iso.json

@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.olimex.com/Products/IoT/ESP32/ESP32-POE-ISO/open-source-hardware",
   "vendor": "OLIMEX"

boards/magicbit.json

@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "http://magicblocks.io/",
   "vendor": "Magicblocks.io"

boards/pycom_gpy.json

@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://pycom.io/product/gpy/",
   "vendor": "Pycom Ltd."

boards/tinypico.json

@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.tinypico.com",
   "vendor": "TinyPICO"

boards/ttgo-t1.json

@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://github.com/LilyGO/ESP32-TTGO-T1",
   "vendor": "TTGO"

boards/wemos_d1_mini32.json

@@ -28,7 +28,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.wemos.cc",
   "vendor": "WEMOS"