Input: gamecon - store object at correct index

The variable i is used to check the port to attach to and we are
supposed to save the reference of struct gc in the location given by
gc_base[i]. But after finding out the index, i is getting modified again
so we saved in a wrong index.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: a517e87c

 ("Input: gamecon - use parallel port device model")
Signed-off-by: Sudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>