V4L/DVB (13445): cx18: Use per cx18 instance init data for ir-kbd-i2c instead of const data

This change creates per cx18 instances of IR_i2c_init_data for handing over
initialization data to ir-kbd-i2c, since that module wants non-const data
even though it never modifies the data.

Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>