iwlwifi: introduce trans_ops->stop_hw

This handler stops the HW and puts it in low power state.
It will allow to clean up the flows in the upper layers.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>

diff --cc drivers/net/wireless/iwlwifi/iwl-agn.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-core.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-shared.h
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-trans-pcie.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-trans.h
Simple merge