scd: change default value of pinpad maxlen

[Alina Friedrichsen]

> Thanks, your patch works fine! :)
> Is it possible to create a white list with all working readers
> over pcscd? So that they don't need to set "enable-pinpad-varlen"?
> 
> gpg1 shows me:
> gpg: detected reader `REINER SCT cyberJack RFID komfort (2111521960) 00 00'

It works too with "REINER SCT cyberJack RFID standard (4964284304) 00 00".
0c4b:0500

Alina