iwlwifi: mvm: add missing mvm ref debug print

IWL_MVM_REF_PROTECT_CSA is missing from the ref strings
used by debugfs.

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>