Wifi: Support check on device capability for 6GHZ

This commit implements support of checking whether device supports 6GHz band.
To accomodate the new feature as well as any future features, feature_set type
was changed from int (32 bits) to long (64 bits).

Bug: 139354972
Test: Manual
Change-Id: If002d8efb854d50af314794926fbdfdc4fb08a5e
1 file changed