[media] au0828: don't let the IR polling thread to run at suspend

Trying to make au0828 to suspend can do very bad things, as
the polling Kthread is not handled. We should disable it
during suspend, only re-enabling it at resume.

Still, analog and digital TV won't work, as we don't reinit
the settings at resume, but at least it won't hang.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>