giga: remove bundled ethernet library

ETH PHY pins are not exposed

Author: facchinm

giga.variables

@@ -1,5 +1,5 @@
 export FLAVOUR="giga"
 export VARIANTS=("GIGA")
 export FQBNS=("giga")
-export LIBRARIES=("doom Ethernet MRI Portenta_SDRAM SPI WiFi ea_malloc openamp_arduino STM32H747_System ThreadDebug Himax_HM01B0 PDM Portenta_Video USBAudio KernelDebug Portenta_Audio RPC USBHID Wire Portenta_lvgl Camera rpclib USBHOST mbed-memory-status Portenta_SDCARD Scheduler USBMSD SocketWrapper GSM GPS MCUboot")
+export LIBRARIES=("doom MRI Portenta_SDRAM SPI WiFi ea_malloc openamp_arduino STM32H747_System ThreadDebug Himax_HM01B0 PDM Portenta_Video USBAudio KernelDebug Portenta_Audio RPC USBHID Wire Portenta_lvgl Camera rpclib USBHOST mbed-memory-status Portenta_SDCARD Scheduler USBMSD SocketWrapper GSM GPS MCUboot")
 export BOOTLOADERS=("GIGA")