iwlwifi: mvm: don't set K1/K2 for AES-CMAC

According to firmware engineers, the firmware has never required
these fields and the values have always been calculated, they were
just leftovers from a previous implementation.

Therefore remove the unnecessary calculation.

Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>