wifi(interface): Use the "bitfield" type for masks

Change all the variables representing masks to the new bitfield type
in all the Wifi HIDL interfaces.
The generated code will still produce the underlying type of enum as
param. So, no changes are needed in the implementation.

Bug: 33358724
Test: Compiles
Change-Id: Id2e5dee2ce1f1ec8e744aa1c81d3cb9c66e7fc39