The global aggregation size is only set to firmware once
when vdev is created. And the size may be modified
dynamically for a specified AP during association, according
to the OUI based aggregation size configured by ini
'cfg_tx_iot_aggr'.
If global AMSDU size is 0, considering the case as below:
1. connect to AP-1 which is included in 'cfg_tx_iot_aggr',
the AMSDU size will be set to the specifed value.
2. connect to AP-2 which is NOT in 'cfg_tx_iot_aggr',
it doesn't reset the AMSDU size to 0, and firmware is
still using the value set in step #1, it's wrong.
To fix this issue, set the global size for each vdev start,
as init values for each connection.
Change-Id: I790d580fc5762e6816e840ba5484b3cd758334df
CRs-Fixed: 2918046
6a9129e9ea