When LE Data Packet Length Extension is supported, then actually
increase the suggested default data length to the maximum to enable
higher througput.

< HCI Command: LE Read Maximum Data Length (0x08|0x002f) plen 0
> HCI Event: Command Complete (0x0e) plen 12
      LE Read Maximum Data Length (0x08|0x002f) ncmd 1
        Status: Success (0x00)
        Max TX octets: 251
        Max TX time: 2120
        Max RX octets: 251
        Max RX time: 2120

< HCI Command: LE Read Suggested Default Data Length (0x08|0x0023) plen 0
> HCI Event: Command Complete (0x0e) plen 8
      LE Read Suggested Default Data Length (0x08|0x0023) ncmd 1
        Status: Success (0x00)
        TX octets: 27
        TX time: 328

< HCI Command: LE Write Suggested Default Data Length (0x08|0x0024) plen 4
        TX octets: 251
        TX time: 2120
> HCI Event: Command Complete (0x0e) plen 4
      LE Write Suggested Default Data Length (0x08|0x0024) ncmd 1
        Status: Success (0x00)
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>