media: ite-cir: in_use is not needed

The in_use variable is set to true when a lirc file is opened, and ir
transmit can only be done by writing to a lirc file descriptor. As a
result when in_use is read, it is always true, so we might as well remove
it.

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>