wifi: iwlwifi: mvm: set A-MSDU size on the correct link

The existing code sets the max A-MSDU size to the deflink, set it
on the given link instead.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240510170500.4de5c1a031ca.I063bc1508e5068b32e321b0f268bc51dba0c0747@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>