wifi: iwlwifi: mvm: debugfs: add entry for setting maximum TXOP time

Add an entry for setting the maximum TXOP time in microseconds.
The configured value can be read from the same entry.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240510170500.b8d17a9c1731.I57c33574a61edd68bd0ec1aa7009f31111fd7efe@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>