NULLify rfkill pointers during initialization. This prevents dereference
of invalid pointer in case the driver is rebound and some rfkill device
isn't detected anymore. Clear them also in hp_wmi_rfkill_setup failure
path so that an rfkill initialization failure doesn't need to be fatal
for the whole driver.
Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
Signed-off-by: Matthew Garrett <mjg@redhat.com>