[INFO] I2C fallback driver added

[Giovanni]

Hi,

I added a bit banged I2C driver to the HAL, it can be used when an HW I2C is not present or not usable/reliable.

It sits on top of the PAL driver so it should be usable on any platform. In order to enable it on the STM32 put "USE_HAL_I2C_FALLBACK = yes" in the Makefile, it will replace the default LLD.

Note that delays are implemented using osalThreadSleep() so the data rate is slow but the driver is thread friendly. If you want an higher data rate then you can provide an alternative delay function in the configuration structure. The delay unit represents half bit time

To be tested, I don't have much time right now.

Giovanni