iwlwifi: mvm: remove users of nvm_data->valid_tx_ant

In commit 332235427a566d8be04b9676a7ac380c8853aa9b
"iwlwifi: mvm: take the valid_{rx,tx}_ant from the TLV"

I replaced the access to nvm_data->valid_tx_ant to an inline
cheking the TLV flags but forgot a few occurences. Fix that.

Change-Id: I92daac735b46738d97fe2dbd5934bb177fd0751b
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-on: https://gerrit.rds.intel.com/12308
Tested-by: IWL Jenkins
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>