iwlwifi: parse_tlv functions set the fw_version string

struct iwl_fw contains a string that describe the fw. This string
is now set by the iwl_parse_*_firmware.
This string is later used to update the cfg80211 data.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>