iwlwifi: dbg: support multiple dumps in legacy dump flow

Support multiple debug data collection triggers in legacy flow.
Utilize the already existing Yoyo infra so the change is rather simple.

Signed-off-by: Shahar S Matityahu <shahar.s.matityahu@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200417131727.5be6a1923cbe.I10701236b03f66328041f2a38f5f0f22a26fd40b@changeid