Fix: generic_esp32_8mb firmware did not boot

we need to set board_upload.flash_size = 8MB for the firmware to
actually boot using the 8MB partition scheme.

platformio.ini

@@ -86,6 +86,7 @@ board_build.partitions = partitions_custom_4mb.csv
 
 [env:generic_esp32_8mb]
 board = esp32dev
+board_upload.flash_size = 8MB
 build_flags = ${env.build_flags}
 
 
@@ -131,6 +132,7 @@ build_flags = ${env.build_flags}
 [env:olimex_esp32_poe]
 ; https://www.olimex.com/Products/IoT/ESP32/ESP32-POE/open-source-hardware
 board = esp32-poe
+board_upload.flash_size = 8MB
 build_flags = ${env.build_flags}
     -DHOYMILES_PIN_MISO=15
     -DHOYMILES_PIN_MOSI=2