smartcard descriptor: the lcd layout is two bytes long

Change-Id: Ie8fd82d652a9a3fc1d3139ab610bbaa7a5ecd32d
Reviewed-on: https://code.wireshark.org/review/4662
Reviewed-by: Martin Kaiser <wireshark@kaiser.cx>
Tested-by: Martin Kaiser <wireshark@kaiser.cx>
(cherry picked from commit 15f23c735b6ebeb040e2dddce74c31dc7e309312)
Reviewed-on: https://code.wireshark.org/review/4665