wifi: Fix bridged interface property and allociation

1. The concurrent property name over the limitation.
Rename the property name.

2. When allocate bridged iface name, it needs to increase the idx to
avoid two ifaces use the same name.

Bug: 162686273
Test: atest -c VtsHalWifiApV1_0TargetTest
Test: atest -c VtsHalWifiApV1_4TargetTest
Test: atest -c VtsHalWifiApV1_5TargetTest
Change-Id: I388cdd812bd0448c03ad5ae982547629c1e5eff9