TxTimer Calculation not done for all Configuration orders

This issue is just relevant if the Bus Synchronous mode with reduced round-trip time get configured by the startup flag SIII_SL_AP_SET_CONFIGURATION_DEVICE_PROCDATA_MODE_SEPARATE_AT_CALLBACK.

The TxTimer Interrupt is calculated out of the values t1, t5 and tCyc. The calculation is just done if all values are available. The calculation function is just called if t5 was written. This is wrong, the calculation function must be called if each of the values get written. The order of the IDN writes is not defined.