iwlwifi: mvm: print the version of the firmware when it asserts

This can be useful to be able to spot the firmware version
from the error reports without needing to fetch it from
another place.

Cc: <stable@vger.kernel.org> [3.10+]
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>