wifi: iwlwifi: set step_urm in transport and not in the opmodes

This has nothing to do with the opmode. Set it in the transport layer
instead.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Tested-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Link: https://patch.msgid.link/20250423091408.4e288f7897be.I0c8f792ea2ed6967f8c6d8181f9c5f74bbec7d18@changeid


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