iwlwifi: move rfkill status handling out of transport

The transport layer should only check the
hardware RF kill status, not impose any
policy or reaction based on it, so move
that out of it into the op_mode.

For now keep the restriction on loading
firmware, that will have to be removed
later.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>