Bluetooth: Add support for local OOB data with Secure Connections

Bluetooth: Add support for local OOB data with Secure Connections

For Secure Connections support and the usage of out-of-band pairing,
it is needed to read the P-256 hash and randomizer or P-192 hash and
randomizer. This change will read P-192 data when Secure Connections
is disabled and P-192 and P-256 data when it is enabled.

The difference is between using HCI Read Local OOB Data and using the
new HCI Read Local OOB Extended Data command. The first one has been
introduced with Bluetooth 2.1 and returns only the P-192 data.

< HCI Command: Read Local OOB Data (0x03|0x0057) plen 0
> HCI Event: Command Complete (0x0e) plen 36
      Read Local OOB Data (0x03|0x0057) ncmd 1
        Status: Success (0x00)
        Hash C from P-192: 975a59baa1c4eee391477cb410b23e6d
        Randomizer R with P-192: 9ee63b7dec411d3b467c5ae446df7f7d

The second command has been introduced with Bluetooth 4.1 and will
return P-192 and P-256 data.

< HCI Command: Read Local OOB Extended Data (0x03|0x007d) plen 0
> HCI Event: Command Complete (0x0e) plen 68
      Read Local OOB Extended Data (0x03|0x007d) ncmd 1
        Status: Success (0x00)
        Hash C from P-192: 6489731804b156fa6355efb8124a1389
        Randomizer R with P-192: 4781d5352fb215b2958222b3937b6026
        Hash C from P-256: 69ef8a928b9d07fc149e630e74ecb991
        Randomizer R with P-256: 4781d5352fb215b2958222b3937b6026

The change for the management interface is transparent and no change
is required for existing userspace. The Secure Connections feature
needs to be manually enabled. When it is disabled, then userspace
only gets the P-192 returned and with Secure Connections enabled,
userspace gets P-192 and P-256 in an extended structure.

It is also acceptable to just ignore the P-256 data since it is not
required to support them. The pairing with out-of-band credentials
will still succeed. However then of course no Secure Connection will
b established.

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>