iwlwifi: dbg: check trigger data before access

Without trigger data set, no point in any collection.
so check that we have the info for collecting the data.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20220304131517.5fb34fb1f0eb.I4d7f2a4d162e80474540c5caf1194ed7d32977bc@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>