iwlwifi: remove module loading failure message

When CONFIG_DEBUG_TEST_DRIVER_REMOVE is set, iwlwifi crashes
when the opmode module cannot be loaded, due to completing
the completion before using drv->dev, which can then already
be freed.

Fix this by removing the (fairly useless) message. Moving the
completion later causes a deadlock instead, so that's not an
option.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>