SAMD device cannot clear external i2c eeprom

[tbowmo]

Reported on the forum:
https://forum.mysensors.org/topic/8814/cleareprom-does-not-work-for-sensebender-gw

When clearing eeprom, operation is halted.

[tbowmo]

Writes is halted in SERCOM module under arduino, when writing single bytes to the eeprom.

[tbowmo]

We are not initializing HW propperly, when using MY_CORE_ONLY, so I2C bus is not working

[GregerLindblom]

Seems to still be an issue when running SensebenderGatewaySerial sketch from development branch. Execution halts when Wire.endTransmission(); is hit in extEEPROM.cpp.

I2C hardware probably still not initialized correctly.

Btw shouldn't MY_EXT_EEPROM_SIZE be 32 kbits?

[pbolduc]

Moved to #1322