iwlwifi: pnvm: don't try to load after failures

If loading the PNVM file failed on the first try during the
interface up, the file is unlikely to show up later, and we
already don't try to reload it if it changes, so just don't
try loading it again and again.

This also fixes some issues where we may try to load it at
resume time, which may not be possible yet.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Fixes: 69725928 ("iwlwifi: read and parse PNVM file")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20210115130252.5ac6828a0bbe.I7d308358b21d3c0c84b1086999dbc7267f86e219@changeid