Bugfix data synchronization after RTE start: In previous version invalid data may be transferred in case the communication is corrupted directly after RTE startup. Root cause was that the data was evaluated without caring if a communication error was reported. In the new version the startup condition and evaluation of data is only done if valid data has been received by the RTE => SPI communication is up and runnig.

Imported from Ac6/SystemWorkbench/plugins/fr.ac6.mcu.firmware_1.14.7.201711101414/resources/builtin/:
* File syscalls.c