f3 i2c: fix first transfer for callbacks as well
f4 pios_i2c: removed useless sempahore action for callback transfers
f3 pios_i2c: removed useless semaphore action for callback transfers
f4 pios_i2c: refactored code to remove i2c_adapter_callback_handler
f3 pios_i2c: refactored code to remove i2c_adapter_callback_handler
f4 pios_i2c: refactored usage of portEND_SWITCHING_ISR
f3 pios_i2c: fixed formatting
f4 pios_i2c: fixed formatting
Merge pull request #779 from lilvinz/fix_f3_i2c

f3 i2c: fix first transfer for callbacks as well