libcacard-CRITICAL debug message

I found critical debug message in a log of remote-viewer:

(remote-viewer:93506): libcacard-CRITICAL **: 16:51:59.273: file src/vreader.c: line 86 (apdu_ins_to_string): should not be reached

@jjelen told me this is just an old debug message, which should be removed and thus not confuse users any more.