wifi: iwlwifi: tighten flags in debugfs command sending

wifi: iwlwifi: tighten flags in debugfs command sending

The only flags that could reasonably be used here are
CMD_WANT_SKB and CMD_ASYNC, CMD_SEND_IN_RFKILL doesn't
really make sense and CMD_BLOCK_TXQS just triggers a
warning, as does CMD_WANT_SKB | CMD_ASYNC.

Clear CMD_WANT_SKB since the response SKB isn't used
anyway, and refuse flags other than CMD_ASYNC to avoid
the warnings or other issues.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Link: https://patch.msgid.link/20260512222731.71b8cda9c4e8.I0cccfd67675989b48d003833f5813c8fbded45a6@changeid
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>