Update d32_pro boards.txt (#4704)

Author: tobozo

boards.txt

@@ -1854,6 +1854,8 @@ d32_pro.menu.UploadSpeed.460800.macosx=460800
 d32_pro.menu.UploadSpeed.460800.upload.speed=460800
 d32_pro.menu.UploadSpeed.512000.windows=512000
 d32_pro.menu.UploadSpeed.512000.upload.speed=512000
+d32_pro.menu.UploadSpeed.1500000=1500000
+d32_pro.menu.UploadSpeed.1500000.upload.speed=1500000
 
 d32_pro.menu.DebugLevel.none=None
 d32_pro.menu.DebugLevel.none.build.code_debug=0