iwlwifi: mvm: implement rate_update hook in rs

Re-initialize rs when we get a rate_update hook called which
happens when remote STA changes bandwidth or sends a VHT opmode
notification.

Signed-off-by: Eyal Shapira <eyal@wizery.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

diff --cc drivers/net/wireless/iwlwifi/mvm/mac80211.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/mvm/rs.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/mvm/rs.h
Simple merge