[media] ite-cir: initialize use_demodulator before using it

Function ite_set_carrier_params() uses variable use_demodulator after
having initialized it to false in some if branches, but this variable is
never set to true otherwise.

This bug has been found using clang -Wsometimes-uninitialized warning
flag.

Fixes: 620a32bb ("[media] rc: New rc-based ite-cir driver for
several ITE CIRs")

Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>