[media] lirc_dev: store cdev in irctl, up maxdevs

Store the cdev pointer in struct irctl, allocated dynamically as needed,
rather than having a static array. At the same time, recycle some of the
saved memory to nudge the maximum number of lirc devices supported up a
ways -- its not that uncommon these days, now that we have the rc-core
lirc bridge driver, to see a system with at least 4 raw IR receivers.
(consider a mythtv backend with several video capture devices and the
possible need for IR transmit hardware).

Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>