scardcontrol: fix bmPINBlockString value
scardcontrol: fix bmPINBlockString value

The sample code uses a (default) maximum PIN size of 8 digits.

bmPINBlockString is defined as "Defines the length in bytes of the PIN
block to present in the APDU command" so shoudl also be 8.

Thanks to Martin Elshuber for the bug report
"[#315675] scardcontrol.c - bmPINBlockString - shouldn't it be 8?"
https://alioth.debian.org/tracker/?func=detail&atid=410085&aid=315675&group_id=30105

hiranotaka/ccid-scr331-nttcom,hiranotaka/ccid-scr331-nttcom,hiranotaka/ccid-scr331-nttcom,hiranotaka/ccid-scr331-nttcom,LudovicRousseau/CCID,LudovicRousseau/CCID,LudovicRousseau/CCID