pcsc: Fix the include path

The pkg-config file already points into the PCSC directory. This
is needed for FreeBSD where /usr/local/include is not in the
default compiler search path.

On Debian
$ pkg-config --cflags libpcsclite
-pthread -I/usr/include/PCSC

On FreeBSD
$ pkg-config --cflags libpcsclite
-I/usr/local/include/PCSC -D_THREAD_SAFE -pthread