V4L/DVB: ir-core: Add callbacks for input/evdev open/close on IR core

Especially when IR needs to do polling, it generates lots of wakeups per
second. This makes no sense, if the input event device is closed.

Adds a callback handler to the IR hardware driver, to allow registering
an open/close ops.

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