iwlwifi: mvm: update expected tpt tables for VHT

VHT introduces MCS8 and MCS9. Update the expected tpt tables
to include these. Previous expected values for 20/40 MHz
are incorrect in certain cases so fix these as well.

Signed-off-by: Eyal Shapira <eyal@wizery.com>
Tested-by: Efi Tubul <efi.tubul@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>