i2c-parport: define ports to connect

As of now i2c-parport was connecting to all the available parallel
ports. Lets limit that to maximum of 4 instances and at the same time
define which instance connects to which parallel port.

Tested-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>