iwlwifi: mvm: take the radio type / step / dash from TLVs

This data should taken from TLVs and not from the NVM. This
is true for the value written in CSR_HW_IF_CONFIG_REG too.

Also, no need to set the CSR_HW_IF_CONFIG_REG_BIT_MAC_SI bit
for 7000 devices which are the only devices currently
supported.

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