Limit number of SBC frames to fit into single MTU

- Calculate number of SBC frames to fit into single MTU for EDR capable
  remote devices. This makes sure the maximum utilization of the
  available bandwidth, keeping the bitrate at high quality.
- This change helps to address the discrepancy seen with a few available
  2 Mbps headsets which set the AVDTP media MTU size greater than the
  2DH5 packet payload size which eventually forces AVDTP packets to get
  fragmented in the controller. This change ensures packing of the SBC
  frames in a way that AVDTP packet size fits within the 2DH5 payload
  size.
- As packet size is restricted to meet the required bit rate more than
  one AVDTP packet can be sent to the controller in a given iteration
  based on the bit rate requirement.

Bug: 24875861
Change-Id: Icae7656ad563bbbdef65ecbfa15a89b26cf9edb2