wifi: iwlwifi: Use request_module_nowait

This appears to work around a deadlock regression that came in
with the LED merge in 6.9.

The deadlock happens on my system with 24 iwlwifi radios, so maybe
it something like all worker threads are busy and some work that needs
to complete cannot complete.

Link: https://lore.kernel.org/linux-kernel/20240411070718.GD6194@google.com/
Fixes: f5c31bcf

 ("Merge tag 'leds-next-6.9' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/leds")
Signed-off-by: Ben Greear <greearb@candelatech.com>
Link: https://msgid.link/20240430234212.2132958-1-greearb@candelatech.com
[also remove unnecessary "load_module" var and now-wrong comment]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>