Bluetooth: att: Reset ATT timer when retrying on security error

If the remote responds with and security related error the stack tries
to increase the security level to satisfy the remote permissions.
This fixes missing ATT timer reset on security related ATT Error
Response as the ATT operation is considered as complete.

< ACL Data TX: Handle 0 flags 0x00 dlen 7
      ATT: Read Request (0x0a) len 2
        Handle: 0x0084
        TMAS: Role
> ACL Data RX: Handle 0 flags 0x02 dlen 9
      ATT: Error Response (0x01) len 4
        Read Request (0x0a)
        Handle: 0x0084
        Error: Insufficient Authentication (0x05)
          TMAS: Role
           Error code: 0x05
< ACL Data TX: Handle 0 flags 0x00 dlen 6
      SMP: Security Request (0x0b) len 1
        Authentication requirement: Bonding, No MITM, SC, No Keypresses
= bt: bt_att: ATT Timeout

Signed-off-by: Mariusz Skamra <mariusz.skamra@codecoup.pl>