Currently, if it's 11r connection, zero out reassoc_ft_ie in
cm_preauth_success(), it will cause FT roaming failed due to
ft ie loss with reassoc request frame.
Fix is to only zero out reassoc_ft_ie when connection is 11r
and open mode.
Change-Id: I8c1d6ca743b528c4ab0211723a792b14abe5acab
CRs-Fixed: 2976385