If link is disconnected due to Authentication Failure (PIN or Key
Missing status) userspace will be notified about this with proper error
code. Many LE profiles define "PIN or Key Missing" status as indication
of remote lost bond so this allows userspace to take action on this.

@ Device Connected: 88:63:DF:88:0E:83 (1) flags 0x0000
        02 01 1a 05 03 0a 18 0d 18 0b 09 48 65 61 72 74  ...........Heart
        20 52 61 74 65                                    Rate
> HCI Event: Command Status (0x0f) plen 4
      LE Read Remote Used Features (0x08|0x0016) ncmd 1
        Status: Success (0x00)
> ACL Data RX: Handle 3585 flags 0x02 dlen 11
      ATT: Read By Group Type Request (0x10) len 6
        Handle range: 0x0001-0xffff
        Attribute group type: Primary Service (0x2800)
> HCI Event: LE Meta Event (0x3e) plen 12
      LE Read Remote Used Features (0x04)
        Status: Success (0x00)
        Handle: 3585
        Features: 0x01 0x00 0x00 0x00 0x00 0x00 0x00 0x00
          LE Encryption
< HCI Command: LE Start Encryption (0x08|0x0019) plen 28
        Handle: 3585
        Random number: 0x0000000000000000
        Encrypted diversifier: 0x0000
        Long term key: 26201cd479a0921b6f949f0b1fa8dc82
> HCI Event: Command Status (0x0f) plen 4
      LE Start Encryption (0x08|0x0019) ncmd 1
        Status: Success (0x00)
> HCI Event: Encryption Change (0x08) plen 4
        Status: PIN or Key Missing (0x06)
        Handle: 3585
        Encryption: Disabled (0x00)
< HCI Command: Disconnect (0x01|0x0006) plen 3
        Handle: 3585
        Reason: Authentication Failure (0x05)
> HCI Event: Command Status (0x0f) plen 4
      Disconnect (0x01|0x0006) ncmd 1
        Status: Success (0x00)
> HCI Event: Disconnect Complete (0x05) plen 4
        Status: Success (0x00)
        Handle: 3585
        Reason: Connection Terminated By Local Host (0x16)
@ Device Disconnected: 88:63:DF:88:0E:83 (1) reason 4

@ Device Connected: C4:43:8F:A3:4D:83 (0) flags 0x0000
        08 09 4e 65 78 75 73 20 35                       ..Nexus 5
> HCI Event: Command Status (0x0f) plen 4
      Authentication Requested (0x01|0x0011) ncmd 1
        Status: Success (0x00)
> HCI Event: Link Key Request (0x17) plen 6
        Address: C4:43:8F:A3:4D:83 (LG Electronics)
< HCI Command: Link Key Request Reply (0x01|0x000b) plen 22
        Address: C4:43:8F:A3:4D:83 (LG Electronics)
        Link key: 080812e4aa97a863d11826f71f65a933
> HCI Event: Command Complete (0x0e) plen 10
      Link Key Request Reply (0x01|0x000b) ncmd 1
        Status: Success (0x00)
        Address: C4:43:8F:A3:4D:83 (LG Electronics)
> HCI Event: Auth Complete (0x06) plen 3
        Status: PIN or Key Missing (0x06)
        Handle: 75
@ Authentication Failed: C4:43:8F:A3:4D:83 (0) status 0x05
< HCI Command: Disconnect (0x01|0x0006) plen 3
        Handle: 75
        Reason: Remote User Terminated Connection (0x13)
> HCI Event: Command Status (0x0f) plen 4
      Disconnect (0x01|0x0006) ncmd 1
        Status: Success (0x00)
> HCI Event: Disconnect Complete (0x05) plen 4
        Status: Success (0x00)
        Handle: 75
        Reason: Connection Terminated By Local Host (0x16)
@ Device Disconnected: C4:43:8F:A3:4D:83 (0) reason 4

Signed-off-by: Szymon Janc <szymon.janc@codecoup.pl>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>