V4L/DVB (12884): cx18: Eliminate warning about discarding 'const' is assignment for IR init

i2c-kbd-i2c allows a bridge driver to pass information about IR configuration,
but uses a "void *" to pass along what is essentially constant data.  This
change casts a const * to a void * to remove the warning.

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