wifi: iwlwifi: mvm: properly set the rates in link cmd

wifi: iwlwifi: mvm: properly set the rates in link cmd

When a channel ctx is assigned to a link, we set the
LINK_CONTEXT_MODIFY_RATES_INFO to indicate that the rate fields are now
valid. But then we always take the rates of 2.4 GHz regardless of actual
used band.
This is because we are getting the band from bss_conf->chanctx_conf, but
this is assigned only after drv_assign_vif_chanctx returns, so we take
the bands of 2.4 GHz.
Fix it by taking the band from the iwl_mvm_link_info::phy_ctxt instead,
as this has already assigned in this point.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Link: https://patch.msgid.link/20240901071542.11c2d3609609.I8fa59e29b6bb38e5d06f3536d54dfb2c5d5bab11@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>