iwlwifi: treat iwl_parse_nvm_data() MAC addr as little endian

The MAC address parameters passed to iwl_parse_nvm_data() are passed on
to iwl_set_hw_address_family_8000() which treats them as little endian.
Annotate them as such, and add the missing byte-swapping in mvm.

While at it, add the MAC address to the error to make debugging issues
with it easier.

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