AdsDevice: handle to long data gracefully
AdsDevice: handle to long data gracefully

The natural datatype for buffer sizes is size_t. Often we pass
sizeof(something) or some_container.length() to our ADS wrapper
functions Read/WriteReqEx2().
For ADS the on wire format for these length fields is only 32-Bit, so
we should verify that our length fits into these bits.

Signed-off-by: Patrick Bruenn <27dd71a6a4a167461f53ec06010a2a08d399a527@beckhoff.com>

Beckhoff/ADS,Beckhoff/ADS,Beckhoff/ADS,Beckhoff/ADS