Bluetooth: RFCOMM: Initiate DLC

This patch initiate a DLC when user calls connect. It first does
Parameter negotiation and then establish connection to the
dlci derived from channel given by user.

< ACL Data TX: Handle 256 flags 0x00 dlen 18
      Channel: 64 len 14 [PSM 3 mode 0] {chan 0}
      RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
         Address: 0x03 cr 1 dlci 0x00
         Control: 0xef poll/final 0
         Length: 10
         FCS: 0x70
         MCC Message type: DLC Parameter Negotiation CMD (0x20)
           Length: 8
           dlci 3 frame_type 0 credit_flow 15 pri 0
           ack_timer 0 frame_size 30 max_retrans 0 credits 4

> ACL Data RX: Handle 256 flags 0x02 dlen 18
      Channel: 64 len 14 [PSM 3 mode 0] {chan 0}
      RFCOMM: Unnumbered Info with Header Check (UIH) (0xef)
         Address: 0x01 cr 0 dlci 0x00
         Control: 0xef poll/final 0
         Length: 10
         FCS: 0xaa
         MCC Message type: DLC Parameter Negotiation RSP (0x20)
           Length: 8
           dlci 3 frame_type 0 credit_flow 14 pri 0
           ack_timer 0 frame_size 30 max_retrans 0 credits 7

< ACL Data TX: Handle 256 flags 0x00 dlen 8
      Channel: 64 len 4 [PSM 3 mode 0] {chan 0}
      RFCOMM: Set Async Balance Mode (SABM) (0x2f)
         Address: 0x0b cr 1 dlci 0x02
         Control: 0x3f poll/final 1
         Length: 0
         FCS: 0x59

> ACL Data RX: Handle 256 flags 0x02 dlen 8
      Channel: 64 len 4 [PSM 3 mode 0] {chan 0}
      RFCOMM: Unnumbered Ack (UA) (0x63)
         Address: 0x0b cr 1 dlci 0x02
         Control: 0x73 poll/final 1
         Length: 0
         FCS: 0x92

Change-Id: I62a19f624fc4bb89eb9a109a5352fa763c1241d2
Signed-off-by: Jaganath Kanakkassery <jaganathx.kanakkassery@intel.com>