[media] media/rc: fix oops on unloading module rc-core

During modiles initialization rc-core schedules work which calls
request_module() several times to load ir-*-decoder modules, but
it does not wait or cancel this work on module unloading.
rc-core should use request_module_nowait() instead, because it
anyway cannot load modules synchronously or cancel/wait pending
work on unloading, because this leads to deadlock on modules_mutex
between several "modprobe" processes.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>